I think sharp images with the 800/800e will be all about technique, it is going to be much less forgiving than lower MP sensors.
Like Vladimir said "All you need to see a slight blur with a D800 image is to press a "100% crop" button on your computer - while on film you should really print a 20"*30" image, with an enlarger (or a crop with the same ratio)."
Same blur from sloppy technique was there with film...we just didnt have a 100% crop button. I see a difference on a D2Xs using MLU or not and that is only 12.4 MP the difference would be substantially amplified on a 36mp sensor i would imagine. I cant wait to rent one and try it out !