Yeah! Both Dissonants and Quieters would have a limited MP Pool. The difference could be:
Dissonants could still cast magic at 0 MP, but with horrendous effects (self-statuses, misdirected targeting, shooting blanks, etc.).
Quieters would probably have their magical strength be tied to their MP, and once it hits 0, they can't cast magic or would only cast very weak magic. Their own stats, especially agility-type stats, could also suffer at low MP.
Basically, MP for these would be a scale of balance, i.e. deviation thereof. Perhaps a better analogue would be the stat that governs the ability to equip Force Metals in MMXCM, in that once the amount of magic used exceeds the "Max MP", negative effects would begin. Twice the Maximum usable, Dissonants would be uncontrolable Zombies while Quieters would be in a stupor.
Maybe a slight rate of regeneration in the field as a person returns to balance over time (the effect of radiative decay)
(And someone who could use both would be able to "recharge" one set of spells by using the other.)
Now, for Resinators, would they have a stronger effect the further an area departs from balance? Or would they just be able to store magic charges to a certain maximum for use later? (If so, the further an area is from "natural balance", the lower the recharge rate.)
Martial types would likely be the "cooldown" type.
Tally: Not just Disquiet, but Quiet as well. Sliding scale type, though.