^ I agree, you cannot take somebody else's shot and compare to one you have taken, to be completely scientific and accurate, you would have to have both bodies take the same exact shot in the same conditions, then compare.
This is why it will be really interesting to see how those that have 5D and 5DII fare when they pick up the 7D as their crop backups, there will be a TON of threads comparing ISO between the bodies. Part of me can't wait, but the other part dreads it due to all the threads and arguments.
Thats why i cant compare the 30D stuff on I-R's site either because they changed their lighting setup....Also they didnt run the same tests and etc..
To be a valid comparison you have to make the only variable the camera, All other things MUST be equivalent...