Very true David.
Here is another link that is interesting. Actual RAW photos from a 5D iii.
5D ii owners could comment if they think their Mark ii could match these.
It seems RAW up to 6400 is clean, after that around 10,000 is good, 12800 showing signs of degradation and pattern noise.
The D800 samples unfortunately are pretty small so that could hide some noise but it seems ISO6400 appears to be similar.
http://www.ceehere.com/Photography/C...Xhcj&lb=1&s=X3 5D3 ISO 6400 Empire State Building
http://www.ceehere.com/Photography/C...Xhcj&lb=1&s=X3 5Diii ISO 12800 Empire State Building
http://imaging.nikon.com/lineup/dslr...tures01.htm#a1 D800 Empire State Building
Probably different exposures, lenses so for comparisons assume it is the best the respective cameras are capable of considering its a kind of marketing release of sorts.
Greg.