See also Jan 15 entry. Just published in Pushing the Blacks is my take on one reason the D3x images look so good: an exceptionally clean signal path producing near-black areas with minimal noise, resulting in an unprecedented (for a DSLR) ~13 stops of dynamic range, 1.7 stops more than the Canon 5D Mark II. The D3x’s 14-bit lossless-compressed files are just adequate to faithfully record its images, which pushes closely against medium format territory.
As I indicated in my Jan 14 blog entry, DAP readers will enjoy coverage of noise on the D3x, D3, Canon 5D Mark II and Canon 1Ds Mark III, including access to the RAW files. I am putting the finishing touches on that report over the next day or two.