I have both the D800 and D800E. Basically, because I "needed" a new camera in March last year and the D800E was not immediately available, I purchased the D800.
Then, when I wanted a second body so that I could have two lenses immediately available, I opted for the D800E.
Within the limits of my own practice - generally A3+ prints from not less than 10% of the image area - I can detect no discernible difference whatsoever in the images from the two cameras. My conclusion, therefore, has to be that it is not worth paying the extra £300 for the "E"-version. On the plus-side, I have never encountered any of the moiré that was predicted as a potential problem - even in highly textured subjects.