Specifically I'd be interested to know why the D4 has a 13.1 EV range and the D7000 has a 13.9 EV range?
Dynamic range isn't the be all-end all some people make it out to be. Especially when the numbers are theoretically derived like the "Print" DR numbers at DxO Mark are. The "Screen" DR numbers at DxO Mark are a little more realistic. (D4 @ 12.58 vs. D7000 @ 13.23)
The primary advantages of the D4 over the D7000 are in the following areas:
Oh, and that 13.23 EV to 12.58 EV advantage for the D7000 over the D4? It is only at ISO 100. By ISO 200 they have the same dynamic range. At settings above ISO 200 the D4 has higher DR than the D7000. At ISO 1600 and above the D4 has an almost two stops advantage.
Where did you get that? Only at around ISO 75! And the difference is very small, 0.77 EV. Above ISO 100, The D4 is a marvel.
Compare the two cameras at DXOMark, and click on "Measurements", and then the "Dynamic range tab"
At ISO 600 there is already 1 EV advantage for D4...