I think we're all coming up with some good ideas here. Everyone seems to dislike pure invisibility but the variations on it are still really good, like the Killzone method (never played it so I'm going off your description). I assume we'll probably see some of this stuff in the beta.
One thing that came to my mind. If we dont have full stealth but somekind of chameleon/plending or just normal hiding type of stealth system. How will they work if you can change your settings on pc that will remove enviromental stuff? Some games have had that problem. You put your settings on low then you can see stealthers without problem.
It should be more about 3d spotting protection on screen and the mini-map when in "stealth" or in concealment so even if there is no foilage from low settings the player can't spot them for the world to light up with gunfire. Much like how silencers in games make recon type classes "Stealthy" without invisibility. Add on top of that, if there are proper camo wearing units or psyker units with abilities to "camo" via chameleon means they should reflect the ground textures and not the foilage of the area when the camo is activated. Same for shadow type "stealth" where a player class can choose a shadowed area, and wait in it causing their silhouette to blur making them much harder to see as long as they aren't moving. We tend to look for humanoid shapes, so when the silhouette becomes difficult to see its practically as good as invisibility, especially at mid-long ranges. So if settings are too low to remove shadows the players silhouette should still be broken up in some areas to reflect the ground textures at that point.
Ugh I just hope there wont be any 3d spotting. Minimap for something like 10-15m radius would be all right. And I don't have any problems with any kind of stealths. It just gives some nice diversity to combat.
Since all space marines start out as scouts before they receive their full set of super organs the scout marines should have significantly less health and weaker armor. This would also prevent them from carrying any melee weapon larger than a combat knife due to the weight of the stalker bolter. i'm looking forward to wreaking havoc on enemy lines. Preysight activated
Scouts undergo traditional rites, challenges and rituals of the chapter, extensive training in all of the aspects of war (reconnaissance, assault, assassination, handling all kinds of weapons and armor imaginable, tactics, survival skills, anatomy, navigation, scouting and so on and so forth) and study Imperial Creed, litanies, etc not only to prove themselves and get valuable knowledge, but also to hone their mind and body that is only accepting new organs and gene-seed They usually don't start off with a full set but rather get one by one under close observation and patronage of their sergeants. And still it takes some time for those underdeveloped organs to mature and for an aspiring marine to learn to control his body with his mind (they can do that) But by the end of their apprenticeship and not long before joining Devastator squad - yes, I imagine they are basically "young" Marines that never wore power armour before
Just wanna add that nothing says a fully developed spamarine can't use a scout armor and in fact some does use them after initation so I would personaly look at the health levels depending on the level of the character.