With all these astrologian complain threads

[fanservice]

I've healed as both a SCH and an AST in dungeons at 50+. My take:

SCH heals better and more reliably, allowing me to do a ton of DPS (what with having 4 DoTs...). The AST's weaker healing potency means that I have to spend more time healing and cannot afford the time to DPS. The buffs given by cards, even when the best ones are drawn, are not significant enough to justify playing AST over SCH.

Haven't played WHM so I can't compare there.

Get outta my head.

Seriously though, I do think a diurnal sect AST is worth taking with a SCH for full party content. AST + WHM... less so.