Canon 6D Dominates in Low Light Focusing Test vs 5Diii vs 5Dii vs Nikon D600

One of the first things I tested was low light auto-focus in my D600. With the center point very reliable lock was achieved at EV0 ( reasonably fast and sharp ), and somewhat reliable at -1EV. A black cross on white paper was consistent at -1EV, but not normal objects. Keep in mind that at ISO6400 EV0 would be an exposure of 1/8S at f2.8. With my 50mm f1.4 that would be 1/30S, not really where I want to be. The in body AF assist really makes a huge difference and produces fast and consistent results at these low levels. However, the RAW samples I've seen from the 6D at 6400 are not very good, not really competitive with the D600, so I'm not sure what the point is. If EV0 or lower is needed, I will most likely slap the SB-800 on, or use the on-board flash in commander mode to trigger the SB-800 located off to the side.