I'd go with the 710 , without question. Extraordinary knife IMO. It really does carry small for a good size knife. The quintessential Benchmade IMO. But if you already own one then you may want to branch out.
Concerning D2 , I live mere feet from the ocean so the air here is always salty with pretty high humidity during summer and I haven't seen the slightest bit of rust or discoloration on any of my D2 blades. It holds a great edge too. Like someone mentioned : D2 takes a little more patience. But it's not terribly difficult. However , I do think that BM should upgrade the standard 710 blade to something a bit more high-end (at least S30V).
Anyway , I've never been fond of the Grip. It's just not my cup of tea. The Crooked River looks great. But the 710 reigns supreme for me.