I know what you mean, there are many things that affect IQ when comparing bodies from different formats. But in a studio setting with primes stopped down to there peak sharpness the difference is minimal and the highest resolution wins.

If you compare on Bryan's ISO charts the 1D III to the 60D there is a slight sharpness difference at native resolution but nowhere near pulling the same amount of dietail as the 60D especially after sharpening.

Not putting down the 1D II, I think it's a great camera and I have often thought about getting one for a second body for a backup and for a few t hings my 60D doesn't do. But if your requirements for resolution are very high then you will better served with another body.

John.