The D4 video in 2.7x crop mode is REALLY sharp and useful. In the FX mode (using 100% of the sensor) I found I need sharpening post processing using Adober Premiere Pro. I did not need such sharpening using the 5D mkII. However where the D4 video really excel is with its low light performance couple with a good metering system, shooting low light movies turn out to be really good.
I did not compare one to one the D4 and the 5D mkIII video, but I will do so with my upcoming 1DX!
1DX, 24mm f1.4L II, 50mm f1.2L, 85mm f1.2L II, 135mm f2L, 24-70mm f2.8L II, 70-200mm f2.8L IS II : D800, D4, 24 1.4G, 35 1.4G, 50 1.4G, 85 1.4G, 24-70 2.8, 70-200 2.8 VR II