I love both DB and KB snatches and use both often in our CrossFit classes and for my own training. I'm a bit biased towards KBs though for conditioning since I do a lot of heavy barbell snatches and the KB snatches "flow" from rep to rep much easier.
They are really two different movements. The DB snatch is vertical (just like the barbell version) while the KB snatch is rotational (its essentially a very high swing with a lockout at the top). The hip action is very similar in both movements but they are very different.