I alternate carry between my PM9 and my 442 (black 642).
The S&W is a tiny bit larger but has a more organic shape, which makes it seem to print less, both in pocket and IWB. I carry it mostly close to home, as when walking the dogs around the lake, loaded usually with two shotshells and 3 JHP's alternately. Around here I'm more worried about slithery or 4 legged adversaries than someone who might shoot back.
Most of the time, especially when going into hostile territory (you know, the grocery store and stuff) I carry the Kahr with 6+1 Gold Dots and a reload. I like the extra rounds, plus have more confidence in the 9x19 over the .38.
I did have some FTF's in the break in period (about 5 in the first 500 rounds) but none since; up to about a thousand and I feel I can point and hit better and more quickly with the Kahr, though that's pretty subjective. In slow fire there is no comparison; the Kahr is way more accurate.
The Kahr is also more pleasant to shoot, though neither is exactly fun after a box of shells or so. Even with standard pressure rounds the Airweight feels like a firecracker in your hand. You don't notice it as quickly with the Kahr, but after a while you feel every single stipple on the grip.
I really appreciate the value and function of both guns and plan to always keep both, but if I had to choose one...it would be the Kahr.