I have a 5-cleric team at 29. Mine are Justicar/shaman with a couple points in druid for the healy pets. Problem with 'em is the group heals are kinda like Chloro: the DPS-while-healing doesn't stack for the whole group at the same time. You can redirect all healing to the tank but as soon as you start taking heavy AoE damage, the group just falls apart.

Back to my rogue group. :P