I have had some trouble with my P9.
I have found two problems:
#1. I am 6'4" and have long fingers to match. I find that unless concentrate on holding the pistol in a specific way, I have about a 3% chance after each shot is fired of one of my fingers hitting the magazine release during recoil to drop the magazine. It is depressing when shooting to find an empty pistol and a half loaded magazine on the ground or halfway fallen out of the pistol.
#2. I don't like the magazine design. If the spare magazine is stored loose the top cartridge tends to work it's way out. This could be solved by always carrying the spare magazine in a hard leather mag pouch, but that adds bulk. I went mountain biking with the P9 once and when I finished the ride, I found an empty spare mag and 7 loose 9mm rounds in my bike pouch.
I have not experienced either of these problems with any other pistol.
This is why I prefer the Makarov to the Kahr. I love that nice European mag release which works properly as well as a spare magazine that does not unload itself.