>I only produce 20 x 16 or normally 16 x 12inch prints. I don't need bigger images and guess I never will. The question is this, at the same viewing distances will I tell the difference between the D700 and D800/E.
I'd suggest downloading the 100 ISO NEF file for each camera - the D800 shot (42.3MB NEF) is on the LHS and the D700 shot (12.4MB NEF) is in the dropdown on the RHS.
Resize the D800 NEF to 4256 x 2840 (D700-size near as dammit) and save as a JPEG - then compare it with the unaltered D700 NEF (also saved as a JPEG). Look at the print on the batteries and the Martini bottle. That should give you an idea of both cameras when printed at the same size (but not bigger than the D700's native, which I think is 14.19" x 9.44" at 300dpi).