I really don't know how anyone could complain that the D800 is heavy. People whine about just about anything and probably everything. Personally, I find my D800E relatively light compared to my D3 and actually wish it were a little heavier. Some weight helps to steady a shot.
Now the file sizes are another matter. I had to upgrade from my three year old computer because it was sooooo slow processing TIFFS, especially with Nik Software. Plain JPEGS were no problem though.
The D800E is a fantastic camera and the dynamic range and detail are amazing.