I'm on the fence between getting a 5DII and waiting for a 6D. I had a couple of chats with people at Canon Tech Support yesterday (got cut off from the first one so called back a second time). I didn't get any "ground breaking" new information, but both techs I talked to had played with a 6D, so I thought I'd share what I learned.
- As most have already figured out, the 6D is not intended to be a replacement for the 5DII. While the 5DII can be looked at as a "pro" level camera, that is not the intention of the 6D. It is a "pro-sumer" camera intended to be in line with the 7D. That doesn't mean "equal to". Where the 7D's target is sports, the 6D's target is portraits and landscapes. Build-quality, size, etc. wise, though, they are supposed to be very similar. In other words, if you are mainly into sports, go for the 7D, if you are mainly into portraits and studio go for the 6D, but if you want something that will excel at both, you're going to have to fork out the cash for the 5DIII, or have the benefits of both a crop and a full frame by buying a 6D and a 7D.
- The 6D will NOT have a PC sync port. With how common wireless triggers are for off camera lighting, I guess this isn't that big of a deal, but I thought it was pretty odd for a camera that's specifically targeted to be for portraits to not have one.
- While it just has the 11 focus points, it will inherit some of the focus system of the 5DIII, specifically the iFCL technology. The tech's explanation was that, for example, if you are tracking someone wearing a white jersey, it will recognize the color of that jersey and try to keep focus on that object as it moves. When I researched iFCL a bit, it seemed to imply that iFCL does use the focus points to determine where to meter, but it didn't really say that it actually helped AF at all, so whether or not the AF will actually be improved by iFCL is debatable. This may be some new functionality, or the tech may have just been smoking something. Anyone with more knowledge on the subject is welcome to chime in.
- The "silent shutter" mode of the 6D is supposedly even quieter than that of the 5DIII. The tech said he couldn't believe how quiet it was. Of course, this may or may not make a difference to you depending on how you will use it.