The raid doesn't have to be healed up "quickly" until P3. In P1, you only need two crackles and the time constraint is insignificant in that phase, so you have optimal time to push 2 crackles and get the raid up. In addition, you can weave PW:S between heals on the tank to protect people who may dip too low or will die from an impending crackle. P2 you can push one crackle or two. If your healers already have raid healing issues in P1, I would only push one, because very few classes will have CDs for another crackle in that phase. In P3, the two healers healing the nef tank + crackles have so much time to do it because the healing is so stupid easy unless you are healing the add tank, meaning you wouldn't need to be pumping as many raid heals. Disc has a lot more utility for that fight and would be worth considering.