Interesting thread so far, and I'm going to disagree a bit with some of Luke's, Dan's and Ned's comments.
I upgraded fromt he D3 to the D3s because of the increased low light behavior. I passed on upgrading to the D4 because I did not see the improved AF as worth the money. SO obviously I like my D3s.
I also like my D800e. At reasonable image sizes — in other words, when downsizing to 12 mp — the D800 characteristics are as good as the D3s/D4 up to ISO 6400. The AF is a bit of an issue. Usually it's great except then it completely misses. The huge benefits of the D800e for me are (1) wonderful dynamic range; (2) impressive croppability; and (3) the smaller, lighter form factor. Coupled with f/4 glass instead of f/2.8 beasts and I've shaved a huge amount of weight off the package.
The D800e has become my primary body.
Jon Kandel A New York City Nikonian and Team Member Please visit my website and critique the images!