Thanks Bill. That helps clarify my thinking somewhat. I intend to do nothing until the D300s replacement is announced in fear of making a serious and expensive blunder! However, your comment regarding "the D800 in DX Crop Mode will be about equivalent to the D700 in FX and ahead of the D7000" is extremely interesting. Mostly because if the DX crop on the D800 is equivilent to the D700 in FX, I'd certainly settle for that.
I've used my D700 for wildlife with higher ISO settings in FX when I can get closer, in other words making up for the x1.5 APS-C crop distance, then conducting crops with great results noise wise. Far better results than with the D7000 at the same ISO's x1.5 distance further away. If that makes any sense
Interesting stuff and valuable too, better to talk about it here and make a more informed decision.