I too am looking to make the change to FX format. I have a D90 and D7000 combo right now. Looking to go to a used D3 or D700. Is the D3S a better option? I mostly shoot at the Race track where lighting can be difficult. I have been following several sites and there is a substantial price jump from the D700 to the D3 series. I don't mind spending the Money if it is worth the investment.