I was recently looking for a small 9mm which could fit in a pocket and which would totally disappear in a tuckable IWB. After a lot of research I found several guns which would be good for the role, but decided I wanted a CM9 and searched for a local gunshop that had one.
When I found a shop that had one, I went there specifically to get the CM9. At the store, I checked out several small 9mm's back to back (the CM9, LC9, P290, PF-9, and Nano). After checking them out back to back, I ended up going home, not with the CM9, but with the SIG P290.
It is heavier than the CM9 so it isn't quite as good as a pocket gun, but then any 9mm won't disappear like a small .380 will. It does work with a good holster, and it completely disappears with a good IWB holster. I love the P290's night sights, the extra weight makes it handle recoil quite well for a small gun, and so far it has been 100% reliable with any ammo I've put through it. Due to the steel frame J-frame comparable weight (near the limit for pocket carry), I decided to also pick up the Pf-9 or the CM9 for times I wanted something sized between my P290 and my LCP. Once again, upon checking out all the options side by side and dry firing them, I went home with something else (the Pf-9), and if I do eventually get a Kahr it won't be one of the pocket 9's (probably a K9 or K40).
So, while the PM9 and CM9 are terrific guns, I'm not sure I agree that they are the best 9mm. They are darned good guns (my best friend had an MK9 which he traded on a PM9 and they were both great guns), but there are quite a few terrific guns in this niche any one of which could be a good choice.