Thanks for the suggestions everyone. We downed him tonight (10 man) after all mana users got the hang of when to use the green clouds (tip: blow them up during the kite phase so healers can sit in it without fear of the tank getting owned). Our resto druid was doing like... 1k HPS so we had him swap to feral (In unenchanted greens / blues... soooo not passing recruitment). Our Resto shaman and Pally 2 healed it, the shaman died at like 30% and the pally solo healed it the rest of the way: scary as hell btw, as I was hovering around 40% HP praying for the RNG gods to save me.
I managed to keep aggro with zero points into conviction/crusade, and only 1/2 SA in as much of an avoidance set as I could muster! I dropped consecrate from my rotation, and at several points dropped HotR as well. I used only Holy shield, and ShoR after judgements. I built up mana to 90% for when I was going to use wings and went back into a full rotation. Sacrifices were used in the latter half of the fight, but it wasn't really a big deal. The warrior keeping sunder up was nipping at my heals a little, but most other DPS were ok. Mages / locks caught up during heroism. We'll see how the 25man version goes tomorrow night.
On an semi-unrelated note,
http://www.wowhead.com/?item=45313 is amazing. I rotated the use effect with
http://www.wowhead.com/?item=40683 and shield wall. The armor bonus reduced incoming damage from 13k+ after block to around 10k. With over 40K HP it definitely takes some pressure off the healers.