I only bought one and have never had a Keltec or HiPoint to compare it to. But my experience was not positive.

I bought a PM9 a few months after they became available. It was the only really small and light 9mm single stack available at the time. The gun started out being 100% reliable right out of the box even though Kahr recommended a break in. A few hundred rounds later the magazines started falling out and Kahr sent me a metal magazine release to replace the plastic part they used on early guns which fixed that problem but I started to get both stovepipes and nose dives. I replaced the recoil spring which helped but did not fix the problem. So I replaced the Kahr with a Glock 43. I have more rounds through it than the Kahr and the only failures have been the slide sometimes riding over the last round in the magazine when I use extended base plates. I cannot blame Glock for failures from an aftermarket part.

I have to wonder how often people that say their PM9 and CM9 pistols are 100% reliable actually shoot them. For the first 500 rounds or so mine was 100% but it went downhill pretty rapidly after that. I have heard people state that small 9mms are guns that are meant to be carried a lot but seldom shot. Which makes no sense to me. The gun I carry is the one I want to be able to shoot well so the Glock 43 goes with me every trip to the range.

Glock isn't the only company that can make a small 9 that runs well. I have heard nothing but good things about the Shield.