Each has its merit..depending on what its purpose is......
P9..Fullsize grip and comfortably fits more hands than it doesnt. More capacity than the others but only by one...with a flush fitting grip. Light enough to carry for years and slim enough to do it undetected. Dependable, accurate and a good size for a CCW thats versatile enough for a range/home defense gun if you feel the need. My K40 shot better than a Sig today...even surprised me alittle, they are very accurate for their size. Great size for IWB carry with other options as well. Pros...great balance in size, caliber and function...can be carried or shoot at the range. Larger grip is better for quicker followup shots in a defensive situation. Cons..to big for pocket carry in most cases.
Overall, a great Primary CCW and can double as a b/u when needed. Target shooting is nice with this gun and IMO, you will WANT to shoot it more than the others
P9 Covert Same barrel slide etc as the P9, longer barrel will give the same velocity as the P from your defensive round of choice which is important to some. The short grip can conceal alot better than the P9...the grip length is the first thing to make a CCW "print".
The shorter grip will also bring this into the pocket carry realm.
With a short mag for CCW and a back up mag with a Pearce Extension for when you need it or just feel like it...you have a choice which is always good. Pros...velocity that matches the P9 and conceals like the PM9. Carry it anywhere..IWB, pocket or ankle. Cons...the Odd duck of Kahr...great design just didnt catch on..shorter grip may limit followup shots as compared to the P9.
Overall, Great compromise between both. Could be a good Primary CCW and a better b/u gun as well. Not as ergonomic as the P but CCW is a trade off...this is a good example of that.
PM9..the super mini. Shorter both ways and the ulitmate pocket auto, IMO. Short, light and still carrys a big stick. The short barrel will loose a little velocity but its a pocket gun right? Most will live with the trade off. The grip is the same as above and with the shorter barrel, may rise more than the covert...just havent shot one to tell you first hand. Capacity is down from the P9 unless you opt for the longer mag....a good b/u mag but not a primary carry. Pros..damn thats tiny! Put anywhere you feel like it
but its still big enough to shoot well when you need it. Cons..more muzzle rise and less velocity than the others...especially with the short grip which may limit quick follow up shots.
Overall...great pocket/ankle carry and stellar b/u gun. It wont sweet talk you to the range like the P' series will but should still be fun to shoot....
Shoot well