It sounds like q4369 was slightly out of spec, enough to be excluded from sale to LE agencies, but still good enough for self defense.
RA40B is the same exact load as Q4369 as far as I know, only difference being that one passed quality control for sale to law enforcement and one didn't.
And as far as I know, PDX1 is simply re-branded and repackaged RA40B, and it probably has a little looser quality control as well.
This source says RA40B is rated 1070ft/s, probably at the muzzle. PDX1 180gr is listed on the box as 1025ft/s from the muzzle, of what length barrel it doesn't say but I think it's safe to say that it's loaded softer than RA40B.