I rented a P40, P9 and K40 before buying my first Kahr.
I found the P40 to have too much recoil to enjoy shooting.
I shot one mag out of it and finished the box with the K40.
The P9 was fine to shoot. As was the all stainless steel K40.
I ended up buying an MK40 Elite 03 Micro.
It's a great gun.
Reliable, accurate and surprisingly shoot-able with full power 40s.
Although the ~25 oz is small enough for pocket carry, it's a bit heavy for that.
And rides much better on a belt.
I would not want a CM40.
It's going to be too light IMHO.
A CM9, with Speer GDHP 9mm 124 gr +P,
is about as good as it's going to get
for a pocket auto loader.
Just my thoughts on the subject