[turnsout]

A 4000 DPI scan of 135 gives you 21 megapixels. So 36MP with a good lens will easily resolve just as much detail. There is not 60-70MP of information in a 4000 DPI scan, period.

For most films, anything beyond 4000 DPI is just going to help resolve the grain particles or dye cloud shapes. You have to be shooting slow fine grained BW with the best lenses to need more.

[buccal]

For me real grain looks much better than digital smoothness. That is important for big prints.