Printing Dpi vs MP count
Thanku for the links. its quite tech heavy but very informative. Part of the reason behind the original question is that after viewing sample images from the D800 vs D600 vs D7100 I was struggling to see the value in paying double the price for a d800 vs d7100 based purely on pixel peeping only. Yes there is a tiny bit more detail but the d7100 is so good now i think you would be hard pressed to see the difference when the image is printed. That is unless im missing something here. The D600 vs d7100 are are ar as i can see indistinguishable (pixel for pixel)
Pretty much the same discussion that was going on ten years ago about 4 and 6 megapixel cameras.
You are more likely to see differences when the pixels are stretched further by having to crop or printing larger.