i would switch.

affliction lock in front, priest to psychic scream.

but then agian, i draintank with my warlock/imp combo while i solo. having a priest in the mix would mean nonstop killing. with high enough mp5 and spirit on the priest, this means enless renews on the lock, which means endless heals on the lock (renew, siphon life, drain life, haunt), which means endless mana (dark pact, life tap), which means literally zero downtime. drain life + mindflay = mobs never running too far. throw in instant howl of terror, then psychic scream and you have yourself a winner. only down side is that the lock will have a larger repair bill due to it "tanking" everything. glyph of fear, glyph of mindflay and glyph of holy nova should add to this deadliness.

but think about this setup and see if it intrigues you.