Blu, ok.
- It has a fair heal that probably won't cast as fast as anyone but a blm, pld, or smn's cure IV, and probably not that fast (well, faster than a pld, probably)..
- It has supporting spells (Winds of Promy is <3, Diamondhide), but most of its spells are self cast only. You can bet that if a blu could directly, repeatedly, cast animating wall or magic barrier on others, blus would be on the mage line. Blu also, of course, has to equip most of its spells, and to do damage (not even great damage, especially as more and more people get weapons), it has to equip spells it won't even use to further its dd potential.
Blu's have saved key lives, and thus saved the alliance, but noone brings blu as a healer, largely because it can't natively heal outside of it's group.