Haven't shot a PF9, but I think my P11 is an excellent choice for carry. More firepower tan the pF9 I just put it into my small zipped vest pocket for my daily walk today, no problem. and that's with the mag shoe extension. I would definitely recommend that shoe extension or an extended mag, because that extreme trigger pull they mentioned tends to pull your aim off; a longer grip will allow you to maintain accuracy. I thought my P11 was an inherently inaccurate gun till I lengthened the grip with the shoe. Now it's quite accurate.
Not a refined gun, the P11 often requires some extra work or parts to get it to where the owner is comfortable with it. Also, mine currently has the last-shot-slide-lock not functioning. Extremely reliable, though considering it's low price ($249) and lack of refinement. I never carry chambered rounds in any of my semi-autos, so the accidental discharge is more or less non-applicable to me.
What I'm saying is that I love mine, but it isn't as user friendly as other guns, so it may not be for everyone.