Honestly I need to vent on my last few days of researching bodies...from what I've read, you don't know (actually I'm sure you do) how lucky you are to own the D700.
Here's what I've deduced in very short summary over the past 7 days:
I would have the following gear if money wasn't an object:
1. D700 and that Nikkor 14-24 2.8 for landscape/architecture/car shows/etc.
2. Canon 40D with the 100mm 2.8 macro (would love to try the new L version) and the MP-E 65mm 1-5X macro lens (non focusing lens btw)...then the Canon 300mm f/2.8L for nature/indoor sports
3. Of course if money really wasn't an object I would limit the 40D to macro and birding only and get the 5D MkII with the 24-70 2.8L and 70-200 2.8L IS for fashion/portraits
Couple of things I've concluded:
1. never consider any of the HD video capabilities of these bodies...tons of horrible reviews
2. The 50D is too noisy for clean macros...yep that's right my 8.2mp 30D at 100ISO 1:1 no crop was cleaner than the 50D
3. The 7D has has a few minor perks over the 50D (best one being weather sealing) but the noise for macro would still be unacceptable and the current AF issues are hard to swallow for another $800 over the 50D.
Dude...here I have a broken 30D and I can trade up with Canon for $775 a refurb 50D but I don't want it (I think...still spinning every which direction on decisions right now).
I really want a little of both, the light and dark side

-Roy