Do you really want to pay a 5.3k+ premium over the D3 for a mere 42% improvement in linear resolution? Why not buy a D3 for speed and low light, and buy a Canon 5D Mark II for high-resolution full-frame shots for 3.8k, and pocket the leftover 1.5k+ to go party? Very, very few photographers know what they're doing well enough to get this sort of sharpness at the sensor, so for most peeps, D3X images will look the same (or worse) than D3 images.
Buy a D700 instead for speed and ease-of-use, or a Canon 5D Mark II if you need ultimate resolution. I'm serious: the D700 handles much better than the D3 if you don't need the frame rate for sports. :think:
And that's why you can get an A850... D3X sensor at a sub-5DMkii price. Kaboom!