The PM9 is considerably easier to hide in a pocket or on the ankle. On the belt, the CW9 works fine. If you want to carry in pocket or ankle (or bellyband), go for the PM9. If you mainly carry on the belt or in a shoulder rig, the CW9 should continue to serve you well.

The PM9 is more difficult to shoot well than the CW9, which shoots almost like a full-size service pistol (at least in my hands). The PM9 has a shorter barrel and leaves the pinky flailing, so it is harder to shoot well. On the other hand, the PM9 is much easier to shoot well than a J-frame revolver or a KelTec P3AT, since it has much better sights and trigger than either.

I have to agree with Mike about the PM9 being more difficult to shoot, at least for me. I just traded for one and noticed that I shoot consistently high. A member at the range said that it's recoil flip due to the small sized grip and the power of the 9mm. I was simply shooting WWB 115 gr. target loads so I suppose I'll have to learn a new grip technique.
I certainly love the size and it's easier to conceal than my Beretta .32 TomCat. Now if I can only figure out how to hold the darn thing....

Schwazche

I have a MK9 and the PM9 and love them. They are superiorly accurate and so easy to conceal, it's scary. The PM9 is easier to carry because of it's weight, but the MK is a bit more accurate (again because of weight)

I'm actually thinking of going opposite of you and adding a P9 or the CW9 to my collection. My PM9 has the extended magazine that gives a near full grip and makes for a pleasant and very accurate shooter.

Like the others stated, if you want some sort of pocket carry, bellyband, ankle, or Smartcarry/ThuderWear, I'd go with the PM9 simply because a full half inch is shaved off the height and the length. And again, you can buy the extended magazine to add back that half inch on the grip if you wish. So it's kind of like having 2 pistols in one, (in a way).

However, if you carry concealed in a belt or other means (shoulder holster), the P9 is an excellent choice and i'd definitely stick with it as it's a superb shooter for that job.

I just went through the same questions... had a CW9 and wanted the PM9, but worried if it would handle as well. Picked up a PM9 last week and no regrets. Recoil was about the same and accuracy was a little better. Very pleased and wonder why I didn't pick it up sooner. No regrets here.

I have a CW9 and my father has a PM9. The PM is little smaller and a little easier to conceal, but smaller is not always better. I personally prefer the CW because it feels a little more like comfortable in the hand and is easier for me to shoot. I think the extra half inch in barrel length allows me a little more accuracy and will also add velocity to the round. The PM is shorter because the flush magazine holds one less round. It also comes with a extended mag. but then it is not really shorter. Both are pretty incredible pistols, you just need to decide what your needs are.