AST are ok mana wise when things go according to plan (but so are WHM and SCH). However it is the crisis management mode that sees AST really go into over drive on MP usage.

Both SCH and WHM can manage to heal up the party when things don't go according to plan fairly efficiently (without mentioning both have better MP recovery tools in the first place) where as AST are stuck spamming Helios as your only option. This is particularly important during progression as mistakes are natural.

I'm just hoping they address the lack of "oh-shit" button (Essential Dignity should be used fairly regularly for MP management in my opinion). The buffs to the 3 Utility spells will hopefully fix this.