For the most part as a healer DRK should focus on vitality. There should never be a point such as the one last night where I zone into A4 with a DRK with 12.9k health and a DRG with 12.3k health and the DRK was requesting to main tank. I am sorry but if you have only 600 more health than a dps because you have all str accessories (and the only gear they had at 180) you shouldn't be tanking a even ladybug.