A sch self crit buff like warrior has would be a nice unique thing to further separate its style from other healers. For a short duration, crits are guaranteed on your spells. You can set up your crit-adlo deployed for sure a couple times per fight.

Shield stacking from 2 sch probably wouldn't happen unless I'm misunderstanding something. Would make stacking shielder healers more desirable than having a regen one and fights might then be designed for bigger enemy nukes that need a double shield anyway.