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/SCH is a really under rated and all around avoided sub. But in all honesty, /SCH trumps both /BLM, /SMN, and /SMN in a lot of situations.

Penury for WHM’s, Reduced Casting/Recast time for WHM spells, reduced MP cost, along with Celerity for the occasional Raise. Stick a Sublimation in there is icing on the cake. (Assuming there's no RDM in your party)

What does /BLM offer? Slightly larger MP pool and Conserve MP. /SMN? Larger MP pool with a 1MP/tic refresh, which Sublimation and Penury pretty much can replace easily.

My opinion, go /SCH all the way.