Im sure holy would do fine but i can see you ooming really fast. I was FH a lot on our kill with a lot of PW:S. Mana is a bit tighter but if you are shielding the orb soakers for every orb then you should get plenty rapture procs.
Actually even if holy did better id say go disc cause you can give those orb soakers 120k~ shields so yeah stay disc and spam those PW:S!!!
maybe use inner will and spirit food/flasks if mana is tight?
Idk if you're talking about 10m or 25m, but we just killed this a couple days ago and I played as disc and was assigned to heal the raid along side a monk and resto shaman. We used a druid for one tank and a paladin for the other.
Having healed this as Holy (first kill on progress) and more recently as disc because I couldn't be bothered to change spec, I'd simply say play whatever you feel most comfortable with unless your group needs a particular ability (unlikely) Mana is tougher on holy in my opinion, but perfectly do-able. Happy to give more specific tips if required.
I've done this fight both as holy and disc (10 man), but this is the only fight in this tier I prefer to play holy. Atleast in my raid, the extra absorbs isn't really needed for the soakers to survive.
Your healing setup is also important. When I was running with a resto shaman, disc was a nobrainer due to infinite mana (Rapture during mana tides) + healing tide from the shaman.
But then, if you are going with a holy paladin, holy might be more suitable due to divine hymn and really strong AoE healing.
I guess mana might be a bit better in disc, but I've never had any issues with holy regen either.
Go holy and use coh/pom on CD. PoH when needed. Use divine hymn as a mana saver.(let the raid drop for a few seconds then bring em back up with DH)
and use ur mindbender on CD. Cascade is ur best choise in 10 and 25. Use it as needed in 10m and on CD in 25m.
Use spirit food/flask and inner will.
Using spirit food/flask on high gear levels is just bad imo (trading into to spi at a 1:1 ratio).
I would have to disagree with you sir. On an endurance fight like this, the extra spirit is much more helpful than the extra intellect. With the gas doing small amounts of constant damage you're going to want to do more frequent casts rather than stronger casts less often.
Edit: assuming you're holy. If you're discipline, then rock that int food/flask with inner fire and pad meters with big bubbles
The tanks can basically solo survive since the bosses dance the majority of the time. It can be nice to get a spirit shell stacked on each of them for when the dance ends, or just a shield to proc your raptures.
We 2 healed it and I spent most of my time smiting the bosses/strengths and using divine star and mind sear to AoE our 4 stack of adds down while our Monk did most of the raid healing.