Yes, grav will suck, and so will poison.
But you can deploy smartly vs poison (D.Eldar have very few intercept, just deep strike the Wraithknights in). Also, your wave serpents will make quick work (as will your wraithcannons) of their AV10 venoms, so if you get first turn, it's game over.
Grav will just have to be target priority #1. And use the fact that you have awesome movement (Wraithknight jump wee) to stay out of their 18" range until they are dwindled down.
You may get outgunned against IG, and other things that have no problem getting stacks and stacks of S7+ shots, but it'll be a fun list to play!
DAMN YOU, DICE GODS!