When you say "120 is a good target, but grain and sharpness are what might bite us even in 120 size..." you make it sound like 120 fim is still theory. Nay, nay. I shot handheld with various 120 cameras all summer -- ortho film, approx ASA 100, almost indistinguishable from TriX grain under high magnification. I'm actually sitting here this morning writing a series of tutorials for TLF, including diy 6x9cm negatives enlarged onto diy ClBr paper (ordinary incandescent bulb enlarger.) In the meantime, I already have info on TLF, starting here and going for the next three pages.

btw, congrats on the dry plate workshop. I'll be sure to get it advertized on TLF!