As D3 owner (8 months) who is very interested in the D700, I keep reading this notion that the D700 is an overpriced D300FX because the only difference between them is the sensor.
Having attended a couple of day-long Nikon events recently and handled the camera and seen what is under the skin, I have to disagree and say that the D700 is a more compact D3.
Holding the D300 and the D700 side by side should immediately put to rest this idea, but I don't think very many have had that opportunity.
The difference in "feel" between a D300 and a D3 is obvious to anyone who's picked both up. The D700 is in the D3 class -- not the D300 class -- of build and weathersealing. The D300 has a lot more plastic, the D700 is virtually all magnesium like the D3.
So in terms of pricing, the D700 is not "an overpriced D300FX" it is a "bargain D3 compact."