Oh and big advantage when its about dpsing for SCH is that your fairy wont get affected and her heal will still be as strong also Lustrates wont get lower effect than 25% health (actually any buff/debuff on you or target wont change it in any kind) while WHM only has MP costy Stoneskin and Benediction with 6 min cooldown.
MPwise Aetherflow and Energy drain makes a SCH barely run out of MP and fairyheals are even for free. As WHM MP management is needed and SoS only recovers 1060 MP not affected by your gear.