Crit is really iffy considering WHM is all about burst heals and strong AOE heals in particular. Too many "unlucky" crits can be potentially dangerous.

Spell Speed is only really MP-draining if you are in a fight that allows you to nuke for long stretches of time or if you tend to spam heal, the former of which means the fight is probably not going to be an issue MP-wise in the first place, and the latter just being a matter of practice.