I do my sensitometry of negatives with a spot meter (minolta, reading to 0.1 stop), using bright cloud daylight as a light source. At this level of accuracy, and with negatives that are deliberately developed to a contrast of only about 0.5, I get a bit more speed out of the Metol version of Pyrocat-HD than I do from PMK (HP5 roll film). Also, I use approximately half strength Pyrocat-HD (3+3+500) with minimal agitation as described by Sandy on the Azo forum at
Go to Film development and look for the post
Minimal Agitation and Adjacency Effects Sandy King 4/15/2004
I have a feeling that dilute developer plus minimal agitation might be the way to go for speed, rather than strong developer. The reason that I use metol instead of phenidone is that I think I either got a bad batch of phenidone or I made some sort of mistake in mixing (I had a stock solution of phenidone in alcohol, maybe not a good thing). Anyway, I like metol, and the metol version of Pyrocat-HD is very pleasing.
FWIW, I get 320 with HP5+ and 250 with Neopan 400 (both at 0.1 above fb+f for zone I as measured by the same Minolta spot meter, accurate shutter in a Mamiya 6). My maximum print size is 12"x16"