Tried it with shamans and druids. It was fun.

With 5 resto shamans I got maximum healing done and maximum damage. Basically I chain healed everything and when zerged just dropped magma totems and spammed chain heal until everyone around me burned on the totems.

With 5 resto druids it was even more funny because having 5 aoe hots makes you heal 20 people while you still have the tank with 20 hots running on his head. I call it "seed of life" because it looks a bit like when I spam seed of corruption with my locks, but the numbers are just green.

Now the plan is to level 5 priests.