I just bought a Kahr P45 a little over a week ago.
It seems like a quality firearm. It comes with 2 magazines, both with the slightly extended finger floor plate. It has polygonal rifling. It has some pretty sharp and brutal checkering/stippling for my tastes. Not bad in the hand, but will not be pleasant against your gut in IWB type carry. If the gun proves reliable, and is a keeper, I will have to file them down a little. Overall, the quality looks great. Well machined, feedramps very well polished and curved. This is a small .45, and it's thin. Great for carry.
I don't have a PM or P9 to compare to, but this has steel inserts to support the polymer frame. If I had to guess, I'd say that the frame will flex. Hell, even my HK USP frame flexes. I guess that's the price you pay for polymer and lightness. We'll see how that plays out.
I have yet to take it to the range. I will probably take it before the end of the week. I will come back with a range report.
The magazines seem close to the 1911. Virtually identical to the 1911 mags with the exception of the mag catch hole. I am willing to bet I can take a 6 round 1911 mag, dremmel the mag catch just slightly bigger, and have a flush-fitting magazine. Someone told me Kahr has copied the S&W style mags...
This has the machined slide stop, unlike the CW9 or E9 with the MIM slide stop (which snapped in two pieces on me on a rental)
I expect recoil to be stiff. I've shot a 23oz Star PD before, and the recoil was hard. I don't expect it to be that bad, because the Kahr has a higher % of it's height being handle. You can get a FULL grip on it, and the bore-axis is very low to the hand. This should make a big difference (I hope). I'm not the senstive type when it comes to recoil. It doesn't bother me much. I'm just wondering how controllable it will be for follow-up shots. Either way, it's not going to be my range gun that I spray 400 rounds downrange with. It will serve as a carry gun, with 50-75 rounds per range session for function checks and practice/familiarity training.