There's an interesting write up of the "Advantage of a Large Sensor" or something like that on the Mansurov's website. I would refer those concerned about high ISO performance to it. There's even mathematical analysis. My (very simple and rudimentary) understanding is that noise is random, signal is not. So when you downsize from 36 MP to 12 MP, noise is relatively reduced by random cancellation. So the fair comparison between a D700 and D800 would be to first downsize the image from the D800 to 12 MP. A long time ago in a different life I did chemical analysis using Fourier Transform Analysis. I believe that technique is based on a similar idea regarding the randomness of noise vs. the constancy of the signal. I'm not presenting myself here as an expert but I must admit reading the Mansurov's analysis has changed my thinking about the D800. That, plus the surprisingly "low" price has made me re-think buying it. That said, I wish I would have purchased the D700 in 2009, but we can't look back. I agree with Mick that, for what it is, it is a brilliant piece of work.