I've been playing a Necro/Monk primary healer lately. He's only level 8 so it's hard to gauge how things will work at higher levels. I'd rather not level him up only to find out that being a primary healer is impossible.
My reasoning for this combo is that primary healers ave a very difficult time maintaining energy. The Necro primary allows using the Soul Reaping skill which results in generating energy from each death. The Blood oriented Necro skills also allow drawing and shifting life around to other party members. Also minions can be raised as temporary energy storage whenever there are available unneeded corpses and the energy available is near maximum.
In action my 8 in Soul Reaping gives me enough energy to cast a free Orison of Healing (+37pts) anytime something dies. I won't waste anyone's time on going through the specifics but it's a fairly rare instance for me to end a battle with less than 1/2 energy.
But there remains that question of whether or not the lack of Divine Favor, and it's additional healing benefits, will make my Necro/Monk a fine secondary healer, but never a primary healer.
So any answers would be greatly appreciated.