When 3.0 launched I started as AST, did fine until Ravana Story, I knew they'd change things by 3.1 and figured I'd just wait to continue it. After I got a dps to 60 (of which I regret leveling first) I went back to Ast, pre buff. I leveled with my Fiancee who was running Drk. We recently hit 60.

Things to note from that experience. Party Comp is important; your DV run is a red flag with 2 brds even a brd/mch would be slightly better. Until 60, Drk /has/ to keep up with current gear 99% more then either of the other tanks; if their Left side is more then 2lvl below, you're going to see a marked difference for healing them. Dont be afraid to use both Aspected on the tank; even if he's not too low yet.

Key for if its new content, watch 2 different videos for it. This will give you a better idea for Healing Problems in the dungeons.
There are Healer Checks in the dungeons. Be prepared for it. Even suggest holding a Bole, if you've had problems on earlier bosses.