My healing doesn't feel quite as slow with heavy mastery and i don't have to worry about where the heal is going (during light raid damage) because the damage is substantial enough that I know i'm still helping out the raid.
Plus, i must admit, not having to cancel a cast of heal because the shammy has gotten off a healing wave or monk has done their thing and topped a person off is refreshing.
Hell, on some fights i do more dps than the main tank.
I do wish there was some sort of aoe atonement heal that would function much like a monk's spinning crane kick (decent dmg and healing to everything within range) Maybe a reskin of holy nova targetted on an enemy? Healing percentage would need to be lowered though.
Perhaps 30% of each hit spread across the whole raid. It could be tweaked to make it less overpowered and it could solve some of Disc's extra spread clunkiness(which is mainly due to PoH being our bread and butter aoe heal).
Or, as a completely different idea, give us something else to use Evangelism stacks on. A new ability, sharing a cooldown with Archangel, could cause all of our atonement healing to spread across raid members within 40 yds of the target.
Making it somehow equal to archangel so that it's not just another wasted button would take some tuning, but if it could be worked into a viable ability, i'd be willing to give up some of Disc's hotfixed overpoweredness.