See this is how little I know about Eldar TT, I was under the impression Dark Reapers just used a HB equiv as their basic weapon.
For the benefit of the Lamenters space marine, a brief explanation on Eldar squads, and then dark reaper weapons. Eldar squads don't get special/heavy weapons mixed in. Everyone has the same weapon, except the exarch (sergeant equivalent) who can take something either complementing to the squad, or fill a vulnerability. They also don't share the same armour (like space marines) Dark reapers get a power armour equivalent, while dire avengers get a carapace equivalent as an example. On to dark reaper weapons. Squad weapons Reaper launcher-it shoots a marine killing stream of mini missiles. Starshot missile-a one-shot buy that they can take with the reaper launcher. It hurts vehicles. Exarch (our special sergeant like thing) Reaper launcher-no change Tempest launcher-like the reaper launcher, but better! Shuriken Cannon-eldar equivalent to a HB (not as good as the reaper launcher, shorter range, less penetration, maybe will have horde viability). Eldar Missile Launcher-it's like the reaper launcher (shooting a stream of missiles) except it can take all sorts of cool ammo for killing vehicles/hordes/flyers. There's also this cool guy called a Death Jester, who belongs to the space elf circus, dresses like a dark reaper but with smiles, and shoots a shuriken cannon knock-off called the shrieker cannon that MAKES PEOPLE EXPLODE IN POISONOUS FUN! Note-of all the things I want eldar to steal from another codex for EC, it is the shrieker cannon.
IIRC; The Tempest Launcher fires the missiles off in an arc (indirect fire/"mortar"), which gives it a larger AoE.
Yes, tempest launchers are known for their indirect fire, good save! They still have direct fire capabilities with that, so who knows what's going to happen.
I couldn't remember that they also had direct fire So they would (hopefully) be a bit like the Plasma Cannon ingame in that regard, e.g. both direct and mortar mode.
As of 7th, they have the barrage rule, which allows indirect fire or direct fire with line of sight. I'm not sure what's going to happen, but I wouldn't be surprised if the tempest became the plasma cannon counterpart, and the reaper launcher was left as a HB counterpart. It's also possible they'll amalgamate everything into the eldar missile launcher with multiple ammo loadouts for different tasks (the tempest becoming a straight upgrade at this point).
Some of that I knew, like Exarchs being squad leaders and shuriken cannons being HB equivs. I didn't realize aspects were so utterly hamstrung though. No wonder your pitiful and outmoded race is diving headlong towards extinction. I mean whaaaat nah that's cool. So the reaper launcher is likely to be the "basic" reaper weapon.
And now you see what we mean when we say that eldar are much more specialized as an army. When you put an eldar squad on the table, you know exactly what it is supposed to destroy. And yes, the reaper launcher is the basic reaper weapon. As for the pitiful race...