As an old F3hp shooter, I truly disliked Nikon's successors. They added nothing I needed (I already had motor drives) and increased size and weight enormously.
I'm also very happy with the DX format. I now primarily shoot macros and I prefer the 1.5x factor. If wanted to fill the frame with a D700, I'd need to replace my 200/4 macro with the non-existent 300/4, which I probably wouldn't want to use anyway. When I don't shoot macro, I do a lot landscape work. Here I would use FX for it's better wide angle performance, but I don't like the lack of filter attachment on the 14-24, its size and price. The 10-24 is serving me very well now and takes filters.
I plan to buy a D300s fairly soon (based on saving my pennies) because I also want to work with the 85/2.8 PC. Here again, I prefer a DX body, since for macro work the 1.5x is an advantage for me.
Re pro bodies I always thought they were pro if: image quality satisfied artistic or commercial uses and pros found them sufficiently durable for their price point to buy.
For my use the D300s is quite satisfactory, metal body, more features, better weather sealing, 100% viewfinder.
I personally think the D300s a more "pro" camera than the D700 because of it's better finder accuracy, but having spent weeks years ago doing copy work with slide film, that may just be a hot button for me. My D90 is 1% better at finder accuracy than a D700.
So far Nikon doesn't make an FX body I'd buy. The D3 series is huge and the D700 doesn't have the finder accuracy I require. No thanks, not now, not for me.