well, I'm in the process of switching away from the mkII and I'm one of the few people here that actually owns a D800 and has shot with it long enough to form an informed opinion. After 3 days of using it, RAW is the way to go with this bad boy. The level of detail, color, DR, simply blew my socks off. There is just nothing in the canon side that comes close, and it would be a waste to use jpg only unless you have some really good reason to.