The 2560p also has Sandy Bridge. I believe that's the model shown.
My wife and I both use OSX, Clover 2560ps. I wouldn't claim they're "fully functional" - The video on them is not the best. Lots of bugs in iMovie and sometimes when running 1080p video you get vertical lines on screen, and not contained to the video itself.
Perhaps the guy running this site has solved that issue, but AFAIK I have the best running methods I could find from various Hackintosh communities and guides for the model I use.