The D600 is a nice camera, but its high ISO performance is not on par with the Canon 6D. Also Nikon put the same auto focus system in the D600 as is in the D7000, so you have a DX auto-focus system in a FX camera; not a great innovation! Also the Canon 6D has the same body construction as the D600. Additionally, the difference in 4 mp is not noticeable unless you print extremely large. So I do not see any advantage in buying the D600 over the 6D.