Switching from D3x / D7000 combo to D4 / D800 Combo

 would recommend D800, due to slight difference in performance and also its cheaper.

You must be on the fence if you're asking here - can see why, between a rock and a hard place if it's hard to justify the big outlay for both. I can't answer you, but I can ask and throw a few thought grenades: Doesn't the D7000 buffer not concern you... it lasts just over 1 second!!? Think you're right that the D800 is seemingly a D3x replacement, rather than just the D700, though I'm no D3x user, just viewed on paper. Have you missed a lot because you lack a D4? Are those events demanding of an insane high frame rate - 4 fps when there's no 'fast one opportunity spray and pray demanding' action might just mean less to cull afterwards. Do you find your ISOs are just way too high - too hight for the D800? Where are the missed opportunities of shots and where are the opportunities for earning more $? Not sure that helps, but seems getting the the two new bodies and selling the D3x and even D7000 is more than a $3k upgrade and it's a big shift in gear. I'm guessing the D7000 is a legacy as doesn't seem ideal but useful little thing: if the D7000 was useless you'd already have a D3s, although $ matters I realise. Just throwing it out there but why not get a D800 now, save that cash a while longer and give it a wait for Photokina on 18-22 Sept to see if there's anything going on about this rumoured and much anticipated D400 that's supposedly replacing the aged D300s. That D4 looks phenomenal but is it really going to earn you more than a D400 might and pay off the difference in actual cost to you? As you're using a D7000, perhaps instead of totally altering your set up + upgrade, you just upgrade: D800 + the good DX to a great DX (will presumably have a respectable FPS and a buffer to match) and your D3x/D7000 sale will mean it looks a little more of like an asset swapping upgrade than full cash binge. D400+D800 might make more sense with what you have now.