I like PP for 9mm loads and keep it around for such but have been underwhelmed in .38 spl and .45 acp loads. Never did close to the velocities promised using PP in the .45 acp with 200gr JHP Hornady's.

6.3grs of PP behind a 125gr JHP in .38 spl (6.8gr is max Speer #13) produced carbon burning on the outside of the cases indicating not enough pressure to seal the case in the chamber. The maximum load of PP (6.8) and the maximum load of Unique (6.0) produce statistically identical velocities with 125gr bullets in the .38 spl so why use an extra .8 grains.

In the 9mm a 115gr Rem JHP on top of 6.3gr of PP did 1,220 fps average from my Glock 19 with .4 grains to grow to a max load. Using the same bullet 6.0grs of Unique makes 1,256 fps with the same .4 grains to grow to a max load.

PP also has an annoying habit of sticking to everything and is a pain to clean out of the powder measure.

In general I prefer Unique to PP for most applications.