" AF we have discussed to death - most 5DII users seem to find it OK - it works happily in most situations and is still the best in class in low light "
Well that is a ringing endorsement, most find it OK! And they are the owners, not the most unbiased of respondents, the 5D was constantly criticized for its AF performance, everybody took a deep breath when the MkII was announced with a slightly improved version, people have just got used to how bad it is when compared to regular use with a much better system. As for best in class, that is a claim that could only be supported by people who don't use the 5D MkII and the D700, it is just not true in real world use. Wait a bit longer? For three full years, over 36 months, prosumers have had a vastly better option for AF than the 5D MkII.
I might be the minority here, I am a stills shooter, I paid $6,000 for a camera that doesn't have video, it is of zero interest to me, I paid that primarily for the AF. The 5D MkII was a groundbreaking camera with an amazing sensor that will not be truly outclassed for years and years. People will be taking amazing images with them until they can no longer be repaired or get batteries for them, but that is despite the AF, and just because it is "good enough most of the time", doesn't mean others solutions are not better, cheaper, more feature rich in whatever area the particular owner needs etc.
Don't make excuses for Canon, kick them up the butt, don't fawn over new mild upgrades that are vastly over priced. Tell them what we need, sure the 8-15 is a fun lens, but how many circular fisheye images are published? Yet again it is a small sensor video orientated lens. An improvement of the 15mm prime with USM etc would have been a much better idea for still shooters.
I have downloaded the sample images, in Lightroom they look absolutely fine to me, the detail in the library shots is remarkable, compare the portraits of the D800 to the D1x, don't repeat what "has been reported" look at the stuff and make your own decisions.
Nikon have made a remarkable comeback from tragedy, disaster, and devastation both in Japan and Thailand, Canon had, by comparison, a better time of it, what did they do with that time? A $10,000 video camera, four $40,000 lenses, several lenses that have yet to see the real world and a belated 5D MkIII that might equal, or slightly best, or not, the already announced, and downloadable sample images from their competitor that was two generations behind and knocked to their knees not long ago.
Sure Canon cameras "are good enough", Canon corporate performance for stills shooters is not.
Not true, when a reasonable percentage of sensors used by Nikon are created by Sony. And that is a significant part of how Nikon got back in the game. And absolutely, Canon users are benefiting from it no longer being a 1 horse race. Similarly, anyone who has a computer benefits from AMD still snapping at Intel (albeit at a reasonable distance), and Apple users have benefited from all the economies of scale that PC users gave them...
Whereas I agree that Canon need to be kept on their toes, and they do appear to have got lazy - whether we like it or not, we need to wait for 2012 to expire before we can conclude whether Nikon / Sony has kept their lead over Canon or not at a technology level. For most people, printing A3, then I think any of the current or previous generation(s) still suffice. My friend still shoots with his 5D and still hones his photographic technique irrespective of the underlying tech. People he sells to don't care if he used a pin-hole
I however, gave up with the 5D MK II, grabbed a couple of second hand 1Ds and am happy with that decision (but not the bank balance). Yes the 1Ds focusing is much better, and yes I am sure the D700 is pretty damned close also - so given the chance then swapping to Nikon may have been better in hindsight. Like many here, it's the investment in glass which makes me pause...
Having said that, I now face the prospect of upgrading all my lenses (over time) if I want to consider then next 2+ generations of camera tech and so I would not rule out a swap to Nikon, leaving my Canon paired with the 500mm until such time as the dollar and yen rates allow me to replace it also. But that's a decision which I will not conclude until the Autumn when I see what Canon have released.
Finally, and of less immediate consideration, but as the camera market continues to get squeezed, it is easy to see why manufacturers look to other revenue streams. Nikon is in someways lucky, as it does not sell camcorders and so can develop that in their camera. Sony and Canon do. However, with the volume-end of the market being aggressively attacked by smartphones and those manufacturers happy to put APS-C or 4/3 sensors in compact bodies, then I would not wish to be in Nikon's shoes, I would want other revenue streams outside their core business. Sony and Canon have this to fall back on. Oh for a crystal ball to see who will be around in a decade....