I owned a MK40 for years. I carried it as a pocket pistol in a Kramer holster and in a Kramer belt scabbard as a primary CCW. I traded it for K40 Covert so I could have the longer slide and the shorter handle. Best of both worlds for primary IMHO.
The MK40 was more accurate than I could shoot it off hand. Recoil was snappy but I still did a good job with it on combat courses. My family members that shot it nicknamed "The Snapdragon." I can only imagine the recoil on a PM40 would be quite a handful. Not for the inexperienced hand gunner.
These days I have a PM9 for deep concealment that I carry some in that same Kramer belt scabbard as a primary CCW. I have every confidence in it and the 9mm using the +P 115 grain ammo it is loaded with. Recoil is very manageable even for my son that does not have the experience with handguns that I do.
For him there was always the discipline of steel.
Pulpa est valeo