Does exposure affect sensor dynamic range?

As an example of how Bill Claff's "photographic DR" differs from engineering DR consider Nikon's D7000 versus the D4. On the DXOmark site the D4 has an engineering DR of 13.1 stops and an SNR of 45.4 dB at base ISO 100. The D7000 at the base ISO of 100 is shown as having 3/4 stop more DR at 13.87, but it has less maximum SNR at 41.1 dB. Looking at Bill Claff's plots we see that he lists the Photographic DR of the D4 at 10.3 stops versus 10.2 for the D7000, reversing the order of which camera has more DR.

Edit: Note that Bill Claff and DXOmark both normalize their measurements for print viewing conditions.

Note SNR is signal to noise ratio, a measure of how "clean" versus noise a uniform portion of the image at a given illumination level appears.