The Nikon and Canon seemed to have less highlight retention then the A73, XT3, and GH5S. The A73 definitely held highlights best though by a small margin.
It seems like the best way to see how much 10 bit makes a difference is to do a dramatic color grade across all cameras and see if the XT3 and GH5S come out on top. I have already seen comparison's between a GH5 and A7S2 with a heavy color grade and the GH5 held together significantly better.
