Oh, I haven't mentioned why larger=better. Simply put it's about the amount of detail. I did write about how amazing drum scanners are on scanning details from analog film:

But the normal scanners already scan around 30MP which is lots. In case you're european: A company named Silbersalz from Berlin uses movie-film scanners to give you 100MP pictures from 35mm film for very cheap. When I'll have kids that's what I'll enshrine their childhood memories onto.