The death of Presto has moved my good friend, and mentor, Thomas, onto Tri-X. I was earnestly trying to convince him that if he wanted interesting grain, he should have a go at developing it in Rodinal. It’s something of a struggle to explain the differences, and no doubt, almost entirely subjective.
The easiest thing is an example, so here is an extreme case:
(click to see it a little larger)
Tri-X in Rodinal @ 20ºC for 13mins. Gentle agitation for the first 30s, and for 5s every minute. Taken using a 6×9 back on a 4×5 Pacemaker Speed Graphic, and an 8″ Dallmeyer-Pentac f/2.9 lens.
It'll All End In Tears 
And despite the grain there is a wonderful softness about it. Now, to see if he takes it up 🙂
I’ve got about 40 rolls of presto 120 in my freezer- – any idea if you can push 100 Acros to 400 with comparable results?
the furthest i’ve pushed acros is to 200. however, my guess is that if you left it in super prodol for ~9 or 10 mins @ 20ºC you’d get pretty close to 400.