The one aspect of the DxO review of the D600 that did catch my eye immediately was the 14.2 EVs of DR, despite having 24.3 million pixels which is clearly a big step up from the 5D mark III's 11.7 EVs that is a whopping 2.5 stops more!
I think the better DR has to be a function of the base ISO
of the EXMOR sensor in the D600 (which according to DxO the Nikon scores +700 ISO better in low-light sports than the Canon 5D3). I don't know if Nikon's processing algorithms are so much better than Canon's that this could explain away the large technical gap that has apparently opened up between the 2 camera makers
I mean is it hardware-related or software-related? If the latter, then Canon could close this gap pretty quickly without much additional R&D.