Sorry about the arcanemages giving the crit-debuff, just looked that one up in raidcomp and it would be just with specific arcane-specs, which i guess almost no one has. But they still have more support than us.
So either they give us:
More manareg for group (like BC, but i don't think they will)
More groupheal (like 25% on groupmembers too, but i don't think they will)
More dmg (which would make us the best dd-class, so i don't think they will)
A chance to reroll my Shadow to a Warlock
Or they just nerf the support of the other 9 classes, so replenishment and groupheal is enough.