On: Not Long Ago, Lenses Were Much Lighter

>I've shot 6x6 Provia on a Mamiya 6 and had it scanned at 40MP and 80MP final output sizes; the latter was clearly better.

The real test is whether you can find any details visible in the 80MP scan that are lost if it's downsampled to 40MP.

The 80MP scan passed that test for me.

I don't think you understand. The wrong comparison is between the 40MP scan and the 80MP scan. The right comparison is between the 80MP scan and the 80MP scan downsampled to 40MP.

I do understand.

Can you give an example of an 80MP scan that loses detail when downsampled to 40MP?