Good point! It would depend on the D3x offering a APS-C high speed crop mode and the frame rate it could achieve. I believe a D300 can get to 8 fps with a supplemental grip. This is 12.4 mp at 8 fps which actually blows the D2x away since the HSC mode is only 6.7 mp. I think the sensor is the same but the Exspeed processor must be that much faster. If a D3x at 10? mp has a frame rate at 8 fps, then it would be a close match for a D300 as a back up to the D3 and then I would indeed only need the two. Dare I hope that such a thing would happen?
Good judgement comes from experience, experience comes from bad judgement.~ Mark Twain