Picked up a second used fullsize PX4 and a used subcompact PX4. The fullsize gave me a few BTF's and then a case got stuck in the chamber so I'm think it's got a bad extractor/spring. Gonna replace both because no reason not to. The subcompact is fairly snappy. I didn't shoot it next to my Glock 26 but if seems snappier than the 26. The PX4 subcompact has a typical Browning-style lockup and uses two equal length recoil springs. I think that the PX4sc might benefit from a recoil spring setup more like the Glock's but there's probably patent issues to deal with. Or since the compact has the same barrel length as a G26, just replace the current PX4sc with a PX4 compact that has a shorter grip, maybe even shorter than the current sc so the mags hold an even 10 rounds and then offer a sleeve for the 13 round mags.
Also brought the M9-22. This thing is a lot of fun. I could burn through a lot of .22 ammo in short order if I had more mags. The only malfunctions I've had were with Winchester M-22 ammo. That stuff is really shitty and inconsistent. I wanted to shoot my .22 revolver I just got but the second round I fired was a squib and blocked the barrel. Recoil was all over the place and a few rounds didn't eject or didn't cycle enough to pick up a fresh round.