Well "life grip" will easily make priests the most hated class in the entire game, all thanks to idiots and jerks misusing it. You could write an entire book on the amount of ways you could single-handedly wipe an entire raid with this power and still have another entire book to write on how to grief with it in non-raid situations...
Seriously coming from the perspective of a lvl 80 combat rogue, lvl 80 prot warrior, and lvl 80 blood dk, I DO NOT WANT THIS POWER IN GAME PERIOD...