Use a slower film speeded up, not a faster film slowed down
An often forgotten statement by Geoffrey Crawley is always worth remembering with our film choices. Crawley, writing in the British Journal of Photography, stated that in his testing a slower film always provided higher quality negatives than a faster film inadvertently slowed down by common fine grain developers. For instance, in my darkroom printing, FP4 Plus gives me a personal EI of 64-80 with Crawley's FX 5 or Kodak's D23 (and little more with D76) whilst PanF Plus gives me a personal EI of 64-80 with naturally speed enhancing developers such as FX 15 Acutol S or FX 55. As we see, both films now deliver the same EI, the same shadow detail, and can be used in the same way, but the PanF will deliver better quality negatives than the FP4.
Crawley went on to say that even if you push a slow film to match EI, such as increasing development time of PanF in D-76 in order to reach the EI of 80, and you accept the inevitable increase in grain size of the pushed negatives, you will still get higher quality negatives from the pushed slow film.
This concept by Crawley has informed the way I view my developer/film combinations, leaning me toward slower films in energetic developers.
Getting the best quality at EI 80.
Film | Developer | Speed | Quality
FP4 Plus | FX 5/ D23 | EI 80 | Good
PanF Plus | D-76 Pushed to | EI 80 | Better
PanF Plus | FX15/FX55 | EI 80 | Best
A slow film, pushed or naturally speed enhanced, will always be better than a faster film.