I've been looking at it for a while, and I do think 15 seconds, even with Assize, is simply too short of an MP regen for WHM to function as well as they should be.

Free Cure, the medica trait, overcure, all of this is assuming that you'll be healing for the majority of the fight.

While it's good for healing, but when DPSing, you really start to see how little MP you have.

Shroud of saints should be moved to 24 seconds like Luminiferous, to combat that MP use that you'll lose while dpsing.