Could you explain this further? I'm not convinced yet. Why then does tonality appear much smoother in a fine-grained slow film (e.g. Pan F) than in a faster film (e.g. HP5+) given the same film size?If you take a minute to think about how film works, it makes absolutely no sense that tonal gradations should be somehow better on larger formats.
All the tonality possible can be contained in a small grain cluster.