3 Healers allows more raid misstakes
2 Healers are better if your raid can avoid standing in fire and interupting adds when its needed, highly reccomended to have atleast one Disc Priest or a Holy Paladin preferably both :P
My list
Jin - 2
Horridon - 2
Council - 2
Tortos - 2
Megaera - 2
Ji-Kun - 1 or 2
Durumu - 2
Primordius - 2
Dark Animus - 2 or 3 depends on tactic
Iron Qon - 3 is much safer but doable with 2
Twins - 2 with a dps drawing
LS - 2