Oh, I think it just might get addressed. For what it's worth, we've got a T8 Mystic that comes out to play every now and then in T8. You need more than just a Mystic healing if you want to survive, but man, when he wards up the tank ... but still, you'll need the right group and they'll have to work well together, just like any other T8 PvP group.
And poison's not overpowered.