I have the CM40 currently, and I'm very satisfied with it. It's very accurate and it carries nicely in a Remora pocket holster. I keep one or two extra 6rd extended mags in the opposite pocket for backup. I did put a set of Talon rubberized grips on it for extra traction.
Recoil is there, but it's not horrible. I had a CM9 too, which was great, and while yes the 9mm CM9 recoils less, the CM40 isn't going to fly out of your hand. I had a CW45, the slightly larger 4" model. Recoil wasn't bad there.
In general, you're going to get more recoil out of a .40 than you are a .45, so if you're alright with a little more than a .45, the .40 will be no problem. I also think the ballistics are better from the shorter .40's vs. the .45 models. Most .45 ballistics come from 5" barrels where as .40's come from 4", so you don't really lose that much with the shorter barrel.
I had a Glock 27 (3.5" bbl) and the 3" CM40 would consistent average faster velocities than the longer barreled G27. Really, there isn't that much velocity loss out of the little CM40, it's only marginally slower than loads from my Glock 23 4" bbl.
Glocks and Single Actions