For me the AF is a deal breaker. Had it had the af capabilities but most importantly the spread of even the older 40/50D AF array I wouldn't have hesitated. I could live with inferior AF compared to the 5DIII if it is priced accordingly. I could live with SD cards and the lack of the joystick but something as important as AF isn't nice to scrimp on.
One thing I would have like to see would be an option like a 6D mod. B that replaced the gps and wifi with a pop up flash. While it wouldn't be used much having one as a back up is always nice for when one is taking snapshots and if it could act as a master it'd be awesome.
There may very well be a "model B" version of the 6D in the future. It seems logical. I owned a 50D for 4 years. The 6D's autofocus is superior to it in most situations. The 50D lacked the ability to tweak the servo mode, for example. It also had less AF points...
The spread of the 6D's AF points alone (and/or the lack of a higher number of points), isn't really that big of a problem. The big problem is all the points other than the center point, are intentionally not
cross type. This is the much moaned about "hobbling". They need not be "double cross", in my opinion. But all the outer ones are one direction only, and not very sensitive in low light. However, I knew this long before I bought, or even tried a 6D.
That aside, as I have said in another thread today...I have nearly 7000 cycles on the shutter since March, and I am very happy with this 6D. It is what I expected, and it performs well for the money spent. The only time I get something not in focus, is if I depend only
on those outer points...while also in low light...and usually in servo mode...with anything that moves even at a moderate speed. So...just don't do that.
Leave them all active, or else use center point only. In servo mode in very bright light with a high contrast subject, you can probably get by with selecting only one outer point.
But for servo mode that is critical, or in lower light...leave them all active and make sure you keep the action at or near the center of the frame. If you're hypercritical about not wanting to do this, you probably already own a 5D3, a 1DX, or something else anyway.
Also the choice of lens seems like it is crucial, for AF speed and accuracy during servo mode. In my experience, the "faster" aperture lens, isn't necessarily always going to achieve focus as fast as a "slower" lens, even if the light is less than ideal. In my opinion there are a lot of factors in play here...certainly the "weak" AF sensor in the 6D needs all the help you can give it, in this situation. So if you know you have a shoot coming up where it's critical, try as many lenses as possible, and mimic the shooting conditions as best you can...to decide which one will work best and fastest with the camera.
If I made a living solely with photography, I would probably own all three...the 1DX, 5D3, and 6D. For my current professional and non-pro purposes, the 6D steps up and is always ready for action. My own goal is to own something with a superior image and AF sensor, to the 1DX...which will hopefully happen with its replacement.
One more point...I'm also perfectly happy with the 6D's video ability. I don't shoot video professionally, and have yet to notice any moire. I know it's there
, but I apparently don't ever shoot anything that will set it off. I guess I just like the low noise, the color and contrast. But I certainly would like to emphasize, that if you ever intend to shoot professional video with a Canon DSLR, just make sure you use a 5D3, likely with the RAW video hack. Before that hack, to me the Black Magic camera looked better...but not since the hack. My non-expert opinion...