LR4 4.3 Released with 6D support
I downloaded the ISO 12800 raws for the 6D, 5D MkIII, and D600 from http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.focus-numerique.com%2Ftest-1566%2Freflex-canon-6d-presentation-caracteristiques-1.html
I then imported those files via LR4.3, kept the defaults, and upsized to 8000 pixels on the long side. It is *very* difficult to see the difference between the cameras. If you downsize to some smaller such as 4000 pixels on the long side, there is essentially no difference.