After messing around with it for a bit, I found that a SMN is going to miss 30 INT a hell of a lot more than a SCH is going to miss 30 MND. Put them all in INT, and don't worry a bit about SCH. It's such a powerhouse healer anyway, when played well, that you're really not going to miss a few extra HP on your cures. The difference is miniscule enough that it really doesn't even matter all that much for SCH.