Depending on how much time you have left on RAF, my suggestion is to level your DK to 70. It should not take long at all as they can fly thru outland zones. You can boost fine at 60 butI have found that leveling my DK up to 70 just for the starter cobalt tanking set makes them awesome. If you only play 2-3 hrs a night you can hit 70 on the DK in a couple days. Their leveling speed in outlands is sick.