I am running a Prot Pally, Holy Priest, Arcane Mage, Ele Shaman, and a Balance Druid, I just hit 83 with my team. I have cleared BRC, TotT, SC, and VP so far. Stone Core was probably the hardest for myself (especially the last boss).

I started the first instances with the same setup i had for Wrath, basically flash heal for any slaves and greater heal for my tank. this worked ok, it seamed to heal enough but flash heal ate into the mana if i got into a situation where i needed to heal my slaves much. I changed flash heal out for heal as it is supposed to be the new "mana efficient" heal.... I found that while it may be efficient, it did not heal enough to keep my team up. The cast time of heal just seems too long for the amount of healing i get out of it. Any time where 2 or more of my slaves were taking damage i just couldn't easily out HpS the incoming damage.

Right now I am using greater heal for all my toons (in addition to PWS and renew if needed) and it is working out much better (but renew also seems to do less healing).

regarding AOE heals, I am not getting much out of them at all. Holy Nova seems to heal for much less than in wrath as does Circle of Healing. I have been meaning to change my AoE heal macro to Prayer of Healing but i have been lazy and not gotten around to that yet.

I guess these are all the changes we get to learn from with the increased health pools in Cata.