Mike, my reasons for a possible switch are
FX against DX, less noise and bigger viewfinder
I don't think I will loose sales. I shot 2 covers this year with my D300 so my publisher is satisfied. But with 21 megapixels you can crop a little.
1080P video, I used to make some video a few years ago
21 megapixels makes printing 60x 90 cm no problem.
I think Nikon isn't coming out with a replacement of the D700 this year if I have to believe the rumours. Or it will be the same 12 megapixels like D3s
My drive for switching is certainly not my desire for new equipment. I shoot nikon for almost 9 years now.
Red Seadiver. How did you come to your discission switching from D300 to 7D. That isn't much of a jump or is it??
Chelydra. I tested myself the AF of D700 with 105 VR makro against 5d mark II with 100 mm IS L makro in my local shop. I didn't see much difference in AF speed as I was repeatedly focussing on the black Nikon lenshood at 1:1 in low light. That surprised me too because I read al the time that the 5d mark II AF is a pain. The 105 VR was hunting some times. The IS L looked like it was slowing down a bit and then it locked the focus.
Before I make my discission I will do some final testing underwater in the real world.