Just bought a used D3x instead of D600 - WOW!

no offense, but that D3x sounds like a pure impulse buy... you have so many questions that one should have answered before purchase, rather than after... i doubt, however, that you'll be terribly disappointed with your purchase. by all accounts, the D3x is a really, really nice body. still, it's your responsibility to do your homework first -- otherwise you might not have lost all those great potential shots with the fuji...