>how much.. the D800 might improve on the D3x image >quality. I doubt it will make a difference. >The D4 looks to be a much better complement to the >D3x, so I think you made the right call.
You are right - if you have a D3x and have no D3s - you should better add a D4. But if you have both D3x and D3s - the situation is different. D4 is even a less a step forward in comparison to D3s. Maybe the most wise scenario is to ignore both new cameras - but NAS forces me to buy at least one of them, and D800 is cheaper