I can see some logic in drk/rng, at least before 20-59. Accuracy Bonus is level 10 for ranger, and would be nice to make up for the hidden accuracy down trait of the drk.
I solo'ed my war as a war/rng, and hit a chain #4 at level 33 with hp in the white at the end thanks to bloody bolts, and weak hitting onions. Ranger sub is underestimated. It works very nicely for thief and samurai in some cases.