IF you take a SCH vs a BLM with equal int and gear you'll find that SMN + Pet out damage the BLM. SMN can outdamage DRG/MNK as well when played properly.
Does that mean they're better? no. BLM has faster burst than SMN - which is required. DRG/MNK have a strong 1 target LB.
SCH heal differently than WHM - they're more DPS + Healer than anything.

They'll tweak them come 2.1, but OP? Ha, classes fit the player and the situation.

But I'll say something, fighting Ifrit with 2 war, 2 WHM, 4 dragoons is a pain in the ass.