WHM has the smallest and most straightforward skill kit to use of the 3 healers and it has amazing MP economy. At level 70 with an AST you need to be able to preplan where to place Earthly Star 10 seconds in advance of the mechanic that demands it and be careful of you MP usage to be effective. For SCH you have to manage Aetherflow Stacks between 3 Healing Abilities, 1 Defense Cool Down and a single DPS tool that doubles as a HP/MP generator. This is in addition to micro managing a fairy and having poor MP economy across the bulk of your spells. If we look at the payout of efficiency at top skill levels the skill ceiling for each Healer matches how efficiently they can be played. It is hardest to master a SCH and it would seem you get rewarded with the most efficient gameplay and highest DPS for doing so. WHM has the lowest efficiency and the lowest skill ceiling as well meaning the Healer balance could possibly be perfect from a perspective of skill versus reward. The outcry seems to be that the easiest Healer to learn should be equally effective as it's harder counterparts and personally I don't think it's fair for that to ever happen. RDM should be the weakest DPS and WHM the weakest Healer. They are too simple to be rewarded otherwise.