D800E, moire, and diffraction.

I'm not sure the concern over diffraction on the D800 is warranted. Either you're shooting a brick wall, in which case, who cares, or you have some parts of the elements closer to you than others and you're trying to get them all tack-sharp. (If you weren't you'd use a wider aperture and not worry about diffraction.)

I haven't seen anyone point out (the obvious) that the extra resolution of the D800 also narrows the in-focus area, which seems like it should be of equal concern in real-world conditions.

So basically the depth/defraction tradeoff with the D800 isn't really any different from any other camera. The only difference is the photos will look worse at 100% crop or if you hold a 20"x30" print up to your face.