i was shooting a commercial on a lit stage with the epic, but i brought my 5Dmk3 to do some tests, there happen to be a stills guy doing behind the scenes photos with a d800, so at lunch we put them to the test.
so, two things; honestly, no one could tell the difference btwn the pictures, we brought them up on true waveform monitors and probably the most expensive monitors that youd ever view anything on...we took a poll, no one could tell the difference of the final results. neither could i.
though there was one thing that did occur that was huge for me, when shooting the tests, we had to slow down the nikons shutter to 1/200th to get the exact same stop as the 5Dmk3 at a shutter speed of 1/500th.
but again the final result was indistinguishable.