Honestly I wouldn't mind seeing Holy reduced to 1.5s cast, it's the last remnant of clip mage and feels awful to play. But WHM having a good aoe (stun) is a small perk for WHM in dungeons.

The only other healer aoe I'd change is AST, since they sorely need help in dungeons. Both a potency buff, possible radius buff and an added effect would be fine. Although Slow is going to conflict with Arm's Length and won't really be as much advantage.

SGE is a dungeon god, SCH is certainly holding up well. Both are fine.