Per David Hobby; "The Strobist":
Hobby rejects the Nikon D600 out-of-hand because it has only 1/200 sync speed. Nice to see someone ragging on Nikon for a change, yet bummer that this is actually faster than the 6D if 1/180 is going to be it.
See article: http://strobist.blogspot.com/2012/09/nikon-d600-think-twice-before-you-jump.html
Hobby relies a lot on the high shutter to overpower ambient light. He says he wants 1/250th.
Just saying, there's no need to savage the OP. He is in good company on this point.
Oops. I swear I am not bumping my own post, but I failed to notice the little "update" at the bottom that appeared since I first read this. He gives a quick "Sheeesh!" to the new 6D and the 1/180th.