Sure FF sensor can give you advantages, better details
Hum... don't think so.
There is no measurable difference in terms of detail between a D2x, D90, D300, D700 and D3. This is coming from someone having own a D2x and still owning a D3 and D3x.
Regarding the lenses, using a DX lens on a FX body can be done 2 ways:
- in DX mode -> only the center part of the sensor is used and pixel count is reduced by a factor of 2.25,
- in full mode -> some of the DX zoom lenses are unable to cover the FX sensor at some focal lenght, but the 10-24 appears to be able to cover FX between 15 and 24 mm for instance. This is still not really recommended in terms of sharpness obviously.
The real question though is "does FX have any compelling advantage for your applications?". My personnal answer is mostly not but considering that you might want to switch to FX some time in the future I would only limit my DX lenses investement to a 10-24 and use FX lenses for the rest of the focal lenght (among which the Zeiss lenses I mentioned are good suspects if AF is not important for you).
and better noise control.
As far as noise control/DR goes, well yes FX does have some advantage all other things being equal. The question is "is DX good enough?". The D90 has shown that Nikon is able to extract amazing DR from a FX sensor, in fact more than Canon could with their excellent 5D (said to be more than enough by most users 2 years ago). Things will only get better and DX still has excellent potential...
Cheers,
Bernard