The only thing i would say I am dissapointed with and I know you might thnk this is really small but twice now when I have been out with a couple of wildlife togs, they have commented on how noisey the shutter is.
The D3 has a louder clunk than the D700 which is why I said it sounded more solid. The D3s has a quiet mode and I heard someone use it this weekend. It is quieter in that mode shooting pics. Not sure I would shoot in that mode all the time though as I don't know if it affects performance in continuous modes.
I know someone who shot a symphonic concert and it was a must to be silent. He built a foam box as movie shooters do to sound proof the shutter clunks.
Wildlifers and birders shoot D300's (cropped sensors) a lot for the subject on pixel ratio. A D700 sounds a little more solid than a D300 but the D3 has an even louder shutter. Distracting? I guess if you are shooting birds or wildlife in library type quiet settings with only the bugs and birds making noise it can be noticeable.
I know of several folks using FX Nikon bodies and I never hear them say a word about needing a quiet shutter on a body. I guess they aren't sneaking up on the wildlife. It's all meant to be shot at a distance anyway.
Regarding your comments about no one being disappointed with the D700, I agree and I hear the same sentiment on Nikon only forums as well as forums with mixed gear members. Everyone is more than satisfied with the D700. It is a fantastic camera and I may go with one as my backup. The ONLY reasons I'm thinking of wanting a D3 line of camera is price, similar battery (no more EN-EL3E's), and the fact that I don't think it is so big anymore.
Someone asked about weatherproofing........Nikon says the D300, D700, and D3 line are environmentally sealed. Doesn't say whether one is more sealed than the other but as a single enclosed D3 line body compared with a body/grip, I would say it is better sealed than the other two for that reason alone.
Go hang out on Nikoncafe and you'll get better feedback than here from Nikon folks who shoot day in and day out in all sorts of scenarios. They have been most helpful for me in improving my photography. This question you ask about the D700 vs. D3 is being asked a lot lately (myself included) due to the price inching closer. I say go try one and see how you think it feels shooting with it in the store or shooting a friends. If you lived near me I would let you shoot mine to see what you think vs. the D700.
Good luck. I think you have enough information now to make the decision. Oh, and don't get me started on what to do with my D300s. I may go all FX!