I have both AST and SCH and cleared all content so far with my static using both jobs. AST is fine, but SCH makes things a lot smoother. Just looking at the stats makes me sad. SCH heals 40% more than the AST (using Diurnal Sect, mind you) and those 40% are all comming from the pet, Lustrate and Indomability i.E. for free. Heck, looking at the numbers, if I constantly keep the Selene buff up it does basically the same than the AST cards, unless I have a really good draw. Not to mention the loss of E4E and Virus really hurt. Add the awesome SCH dps and mana management and it really feels like gimping my friends when I want to play around with cards. Kinda ironic seeing it is supposed to be a support kinda healer.

But once again: You can do all content with every healer combination.