I have posted here, because I want it to be clear that I am not interested in fanboy comments from the Nikon club, or biased anti views from Canon users. I would like to know what those experienced in making large prints (40"+) are seeing with high quality files printed from the D800 compared to the 21-24mp cameras (5DII, III, D3X).

There are a number of reasons why I might be more interested in buying a 5D III (colour balance, handling, AF and frame rate, silent shutter etc) over a D800, but I would be prepared to deal with some of the less good points on the D800 if the very large prints produced are indeed noticeably better on fine detail and 'photo reality'. Can anyone comment objectively, having actually made such large prints?

Please no comments about 'normal viewing distance' or 'why are you making such large prints, its the image that matters' because this question matters to me!