Honestly when you go oom as Whm it's a combination of DPS lacking and/or poor mp management. We are killing HM garuda in 4:07 now -- very close to cut into the 3 min mark; of course when it takes forever it is very hard to sustain healing with garuda + chid + sup ganging up on you. Turn 4 Whm will likely go oom after 2nd dreadnought dies but soon enough SV ballad should kick in. Whm have a naturally larger MP pool comparing to Sch and that gap would expand even further when geared with full Allagan/Af2.