its actually larger than full frame, its medium frame. that's how they can squeeze 50mp in there and still have decent pixel size that will lead to good image quality. that 80mm lens on a medium format camera will view more like a 35mm lens on common place crop frame sensors. its limited to iso 800, but i can guarantee that 97% of the time this is used its under studio lights anyway.
also, the only sales they actually make on these things are to rental houses that will rent them day by day for like $1000, and to companies that have a daily use for super high end stuff. even the LL bean catalog doesn't shoot on something like this.
$8000 is the top end of the 'normal' world, and its the studio-use nikon d3x. 24mp full frame and widely considered to be the best slr in the world. personally i would get the 12mp d3s because of its iso 102,400 capability.
ps the canon full frame studio camera is only 21mp and their high iso camera that can reach iso 102,400 isn't even full frame.