"Currently have a D90, with couple of DX lenses. Was waiting for a D7000/D300 replacement to upgrade, when the D600 came out. How a DX crop photo taken with a D600 would compare to a native DX taken with D90/D7000? at 10.5MP I suspect it is at least at par with my D90, right?"
I seem unable to post some D600 DX (16-85mm 3.5/4.5 VR) images, but I am VERY happy with them in comparison to D80.