I've been looking at upgrading (from the D90) for a while and have had my eye on the d700 and Nikkor 24-70 f/2.8. It's going to cost me the better part of $5000 (or more, depending where I get it from). I've been weighing up whether I need to step that far yet, or if I should instead upgrade to a D300s for now, wait and see what the new offerings are from Nikon over the next few years and then get a d700 (or the eventual replacement) later on down the track.
I've just come across a used D300s with 17-55 f/2.8 for a very good price (approx $1800 less than new replacement). Less than 1500 actuations, Australian sold but no longer under warranty. All checks out in great condition and should all be good. The price of this set up is a major draw card.
There's pros and cons for each - and for me lack of warranty on the D300s is a biggy (considering my D90 has been in twice under warranty!) but the higher ISO performance of the FX body is a plus.
Any helpful advise greatly appreciated! I'll be selling the D90 and the 18-105mm lens regardless of which way I go, so no need to maintain DX for that lens as all other lenses are FX compatible.