I have both the Ruger LCP & the Kahr PM9. I have the Crimson Trace laser on both. Of course the LCP is much lighter & easier to conceal, but your giving up some firepower. I've thought about a 9mm LCP too. If it was just a larger LCP, I'd buy one. The LCP in .380 has virtually no recoil, whereas, with the PM9, you'd better pay attention. I can only imagine the PM40. The LCP has a much nicer looking finish than the KelTecs, and that includes their recent PF9. I was looking forward to seeing one & when I did, I was as unimpressed as when I see their .380. I realize that they are good shooting firearms, but all else being equal, they just look less finished.
I really like the size & feel of the Wilson ADP, it's seems similar in size to the Kahr, just a bit longer. It has a 3.9" barrel & is 16.6 oz empty, the Kahr PM9 has 3" barrel & is 14 oz empty. The ADP is still very concealable, and the fitted grips feel really nice. In spite of having a 10 round clip, the grip still feels thin & I have small hands. As soon as I picked one up it just felt right in my hands. Only after reading of some quality quirks & poor responses from Wilson have kept me from getting one. Hopefully, with Wilson's reputation for quality with their 1911s, that will all be worked out and I plan on keeping my eye on one in the future.