I have no experience with Kahr pistols so I can't begin to help you there. However, let me ask if you have looked at the Glock G-27 which is chambered for the .40S&W?
From just what I've been reading on the internet in various places/forums it appears that Kabooms involving the 40S&W (in any brand of firearm) aren't happening with factory ammo but are generally the result of reloads. Now please don't quote me on that because it is based just on a "feel" for what I've been reading.
Now I'm going to get myself in trouble..... I'm not trying to knock your choice of caliber.... not at all. Nor am I trying to start some kind of "caliber war" and hijack your thread. Also, from what I've been reading on the 'net the relitively recent improvements in self defense ammo there doesn't seem to be much difference in caliber effectiveness from 9mm Luger on up. Once again let me put in the caveat that this is just a subjective comment based on what I've been reading.
Just for the record I went with Glock's G-26, the 9mm, but for many different reasons. Caliber was one as I think 9mm Luger is as small as I want to go but there were many other reasons also... capacity was one, concealability another, reputation of extreme reliability was another, my personal dislike of external safetys another, and the lack of a Kaboom history in 9mm another.
Please Patriot... again let me say I'm not knocking your choice(s) as your reasoning sounds fine to me but since, per your post, it appears you are open minded and still in the "decision" stage for your next firearm I just wanted to give you yet another option/gun to have a look at. :-)