Just tried the D600 at Costco today...

If you are considering a move from the D90 to the D600 you may need to evaluate your lens selection. I read some of the posts in this thread and didn't see that you where using any other cameras. If I've missed something I apologize however, in order to get the most gain from a D600 you'd probably want to mount some FX lens' to it.

Just a friendly reminder... Good luck with your decision.