As DXO has given a near perfect score to the D810, they may have painted themselves into a corner. Their proprietary scale doesn't give DXO much room to heap hyperbolic praise on the next Nikon release.
This really isn't a surprise. DxO and Nikon are inseparably joined at the hip. Plus, all this really means, particularly the new 14.8 stops Print DR number, is that Nikon is cooking their RAW files EVEN MORE. Nikon/Sony's biggest "cheat" is the fact that they clip to black point, instead of offsetting to black point. Nikon cameras just throw away a lot of low-level signal information. The Sony Exmor sensor gives them more room to do that, for sure, but they are still throwing away information.
Canon, on the other hand, does not clip, they offset. So ALL the noise in the deep shadows of Canon's signal is still there (it's always there, in every sensor). Canon could probably achieve better results by using a more significant offset...and at times, as they have improved their sensor tech and increased their bit depth, they have changed their bias offset. It used to be 128 to 256 back in the 10-bit days, it was 512 to 1024 in the 12 bit days. I think it's 1024 or 2048 with 14-bit cameras.
The kicker is that RAW editors don't have to honor Canon's bias offset. The entire RAW signal is stored in Canon's files, and the offset is calibrated with a border of masked pixels. Who knows if editors like Lightroom, or DXO, or Aperture actually adhere to Canon's recommended offset. Even if they do, there is still negative signal information that can be pulled up, and the full noise signal is there. With Nikon RAW images...all that negative (deep noise) signal is simply discarded.
I use DeepSkyStacker and PixInsight to calibrate Canon RAW files for integration into a "stack". I use a 200-frame master bias image to subtract the bias signal from each light frame before integrating it. When the bias is removed from Canon RAW files, the dynamic range jumps by almost two stops...which puts it in the same range as Nikon files...