You are correct Scott by why stop at the 400D sensor? The sensor in a 5D is even better and full frame to boot!
See here
http://www.clarkvision.com/imagedeta...ary/index.html
From this information I have figured out that there is no point going below about 500 ISO with the 5DH as its dynamic range is limited by the 12 bit A to D converter.
Check out where the various CCD's place in the scheme of things! Without extreme cooling they are found wanting!
I have been spurred on by the performance of that cooled Canon DSLR and I am designing a peltier fridge for my 5DH. Even a 10 or fifteen degree centigrade drop in temperature makes a huge difference to the thermal noise.
Bert
PS. Check out which sensor wins in every figure or graph.