Healer MP management is rather lacking for non-SGE jobs right now, in my opinion. In response to this I think some small few changes could be made to improve mp recovery across the board.
AST: Make using cards restore a small amount of MP again. Nothing more than a few hundred, as AST already has the 2000 MP from draw.
SCH: Make recitation compatible with seraphism spells, and dissipation restore a small amount of MP. Again, not a large amount but a nice boost from dissipation would make it a more attractive option outside of just spamming more energy drain casts.
WHM: Either another stack of thin air, or vastly increase the amount of MP restored by assize. WHM has the largest MP cost ratio for their healing spells and two stacks of thin air doesn't really feel like enough in my opinion.
These are just suggestions and I can't really say what the best choice would be but as a SGE main my only other thought is that it feels healer MP recovery is not in line with each other as SGE gets vastly more MP than any other healer over a long period of time.