I was in that same situation with a 6600 on Verizon and I made the switch to Sprint, just due to the fact that I could get the 6800 now on the amazing SERO plan. I find id hard to believe that Verizon is going to bother reinventing the wheel on the WM devices. If anything I'd imagine that they would come out with a red colored theme like Sprint did with their yellow theme, which is as easy as clicking on the theme browser and switching.

The 6700's aren't cheap from what I remember, so I'd say if you're going to spend the money, you'd might as well spend a few extra bucks and get the 6800. Too bad you've got another year on your contract...