in the process of lens testing compared the 5d and new 40d at ISO 3200 - both appear to have essentially the same noise which is correctable in LR. I plan to use 3200 more often.
there's a slight color difference between the two - should get around to calibrating them
image quality in general seems to be more lens/sensor size than camera dependent - the 5d needs GOOD lenses to get sharp corners at larger apertures, the 40d does well with fairly ordinary full-frame glass - but then there's no good way to go wide.
