Yeah, back on topic of the OP, I have an Arcanist that I dread leveling due to this (I'll probably go the route of SCH to 50, healers always win). When I want to level using DF, I just partner up with a tank buddy or healer buddy, that is a win situation! Also, as my WHM, i will proactively seek out the members in FC that need to level characters that have problems in the DF (ranged DPS I'm looking at you!). Just find a Tank/Healer friend as a previous poster mentioned!