'Gladly trade acros for most other film - midrange tones don't work for me. There's a gent on P.N that has some much better luck than I've seen elsewhere with it, but I don't want to buy/store/learn another developer - 4 is enough. I would want acros where high/hard contrast was the major contributor to a composition. If that were in very low light - so much the better. Its the unopposed champ in reciprocity.