but I'm skeptical that anyone can subjectively differentiate between otherwise equal wheels that differ only in diameter by 8mm out of 730mm (about 1%)
I don't blame anyone for feeling that way. In the case of the bikes I have compared, my
1975 CCM Tour du Canada, a
Legnano Gran Premio and a
Sekine SHC270, the difference was noticeable to me. And I am not much of a rider.
It is not just the diameter that impacts ride quality. Tire size, pressures, wheel weights all contribute to a difference in feel, as nearly as I can tell.