Sorry but I really have to disagree with you there. Lore wise Rangers are THE eldar scouting unit simply because they can get right inside the enemy force unseen for a look about (As happened in Path of the Outcast) and can pick off key units even when protected by heavy armor or even pin down entire squads. When it comes to fast aerial reconnaissance or scouting roles Swooping Hawks don't even get a mention in the lore, nada, nothing... literally no indication at all that they undertake that role - which should say something. Now think about how they might operate in game. A graceful and fast flying unit that can kite units and possibly drop grenades in their flight path - they're a distraction and an annoyance at best, ideally suited to tackling melee units in the open where they can keep them running about Benny Hill style while wearing them down. However if they get close to a sizeable enemy force and start taking fire they will quickly disappear in a red mist thanks to their weak armor and low health. Meaning that they can't really gain much scouting information about the composition, size, or structure of an enemy force before they evaporate. Now if all you want to do is fly up to the edges of an enemy force and nibble away at it then Jetbikes are the unit you would naturally turn to... mainly because they have a chance to barrel through, deal some real damage and escape alive. In TT Swooping Hawks only saving grace lies in the combination of their ability to fly high and drop grenades (which is a bit of a gimmick and doesn't warrant their high points cost) as well as their picking up haywire grenades in the latest edition (arguably pretty useful for taking out artillery or skyfire capable vehicles hidden behind cover, though you can probably expect them to die in the process) and possibly as a point capture squad (though again jetbikes are better as they can hold the point). Other than that they have underpowered weapons making them sub-par even for harassment.
Agree. Basically Eldar units are already that swift, that adding directly at launch a pure harassing class at their arsenal wouldn't be, in my opinion, at the advantage of the War Host (more likely a waste of time and energy). We must not forget that we will have to fight very resilient foes wearing power armours or having thick (and smelly) skins: lastblasters can't do much against that. In the other hand, stealth and "teleportation" (as you said it doesn't have to be real teleportation in the code lines) could be a deadly and, indeed, very useful combination if the latter were directed on the position of the precedent. With enough skill and cooperation strategic/tactical points could be taken behind enemy lines and, more important, hold until reinforcements arrive. What I'm trying to say is that infiltration and sabotage shouldn't be the concern of one class alone - it wouldn't involve sufficient forces and destructive potential to get the job done properly. Now, even if we get our stealthy and resilient Striking Scorpions, a deep strike of poorly armoured Swooping Hawks on their position wouldn't be enough to secure and hold a point - they wouldn't even be able to use their grenades while their allies are engaged in close combat! No. I think the most qualified duo for that kind of war is the Striking Scorpion (stealth, heavy armour, good close combat unit) and Warp Spider (teleportation, good armour as well, devastating ranged attack) one.
You can't look at the hawks like if EC was TT, first of all they are a ranged class with jump pack and people never look up, take PS2 as example and look how the LA class can easily murder heavier classes and even max units (c4) abusing the high ground, EC will be very similar, the lasblaster will be low damage high rof (3 str 5 ap assault 3, sounds like a carabine to me) I may be wrong but hawks may possibly have the highest skill ceiling in the game if they have accuracy while in the air to represent them as a hit and run unit, a weak class with high mobility and high rof weapons sounds good to me. Of course it will be better if they could have dual death spinners and dual power weapons but not everyone can be a warp spider.
My thinking was that as they can fly it's very easy to fly above silently and undetected and see the enemies from above while Rangers have to get a line of sight. Pretty much everything Eldar turns to red mist under fire and I think if you darted about enough they can be hard to hit. Personally I've found my Swooping Hawks to be very useful and the lack of power is helped by more fire than some weapons. Disadvantage to Jetbikes is that mines and general obstacles pose an obstacle along with cover which doesn't bother Hawks.
You say that people don't look up, and that may well be true for some people some of the time, but I suggest you have another look at the pre-alpha footage, it's not hard to spot people jetpacking about in that. While it may not be entirely indicative of how the game will be at launch and doesn't tell us much about the Eldar it does give us some idea of the approximate range and style of the marine jumps against which the hawks would be balanced. It's not like the Marines can fly great distances, so the idea that the swooping hawk will be high high up in the sky souring on the thermals while raining down death will probably be far from how it pans out. The reality is more likely to be small fast hops around the battlefield coupled with the ability to launch a bomb in flight as their version of the Assault Marine's charge from the sky groundpounder AOE attack. Secondly the over the shoulder view gives a pretty good view, so it's not like hawks will be able to approach unnoticed. Now as a former player of Firefall I'm pretty used to 'looking up' and have got pretty adept at shooting down bunny hopping jetpackers, so the idea that flying units gain some kind of magical inattention armor or air stealth is kinda weird to me, infact a jump jetting unit to me makes an ideal and easily spotted target... they have no cover, are silhouetted nicely against the sky, and typically move in a predictable arc without sudden changes of speed or direction (not true for marines in their charge phase though) Generally their only defense is their speed and with Hawks the faster they fly the harder it will be for them to target their grenades mid flight.
It worked that way in Space Marine (the video game) as well, but the Assault/Raptor class got away with it because of smaller maps and a charge button after they've jumped. Talking about all factions for a minute, Eternal Crusade will need some sort of horizontal charge for jump pack classes, as travelling in a bunny-hop vertical jump may be fun and faster than walking, but as you say, they "have no cover, are silhouetted nicely against the sky, and typically move in a predictable arc without sudden changes of speed or direction" - and this will be more true in larger maps. But this is where I think Swooping Hawks can stand out. Since I first read about Eternal Crusade, I've always imagined the Eldar faction to have the highest skill requirement, as they are not as tough, but much faster than the other factions. Swooping Hawks can have both a higher and faster vertical ascent, along with a fast glide movement (or instant drop like other classes) if they so choose. Being much faster would negate some of their toughness flaws and not be game breaking because of the less-armour balance. And Warp Spiders would definitely be harder to code for, especially if Swooping Hawks are simply faster. And how would you do it whilst making it balanced? A warp mode where you're hovering but taking accelerating damage over time? An invisible jump move? A blink like a World of Warcraft mage? Don't get me wrong, they're cool, but for the game starting out, I believe Swooping Hawks are the way to go.
As far as the coding, probably quite a bit more difficult than one would expect. The flyers are meant to utilize the higher verticle areas of the map quickly, Most the maps are probably being designed around the idea of flyers and drop in attacks. trying to put a a teleport unit into that mix would be difficult, would the spiders simply be line of sight teleport, if so just appearing on battlement edges rather than dropping in behind an enemy would be really annoying. (appearing on the edge right in line of fire of devastators already shooting at the ground. Or the alternative of being a set distance much like throwing a grenade resulting in some cases of fall damage when assaulting, plus the amount of jumps that would end up with warp spider partially trapped in game geometry would be insanely high even with best coding in the world. Granted seeing warpspider parts sticking out of walls everywhere would be funny, Id rather they remain mysterious and feared, rather than a joke that all the other sides tell everytime they talk about notable fights.
If you follow the links in the OP you can read a couple of different suggestions for how Spider's warp jumps can be made to work, but let's just put a pin in the idea that it would be hard to code for, because that's simply not true! Long story short it can operate in very nearly the exact same way as a normal jetpack (user becomes airbourne and moves quickly allowing them to see where they wish to land) only with the Warp Spider becoming invisible while jumping, making them look to have teleported to everyone else, i.e. they disappear here and moments later re-appear there. This even fits with the lore since they enter another universe (the warp) when they travel. Obviously being able to travel long distances in relative safety and appear unexpectedly is a very powerful strategic ability so there are some things that are suggested to balance this out. 1. The longer the spider is in the warp the higher a chance there is that they will take damage when they try to reappear. (Some Spiders become lost in the warp) 2. They lose the groundpounder AOE charge attack that Marines get as well as wall jumping. 3. They can't attack or heal up while in the warp, but they also cannot be attacked. 4. The warp is of a limited duration. It's trivial to code for and simply requires a visual filter so that the warp spider can clearly see when they are in the warp and a means to allow them to enter and leave a type of spectator mode while warping. Other than that their movement can even be simpler than for a standard jetpacker since they don't get wall hanging or aerial charging.
I would also add this one as an exception of your point 3: 5. Although they can't see them, psykers still can inflict strong AOE damage to the warp-travelling Spider. This would fit well to the lore I think, since a Chaos sorcerer with his aura alone is supposed to make such journey infinitely more dangerous for the Aspect warrior.
