I carried a Kahr .40 (M4043) in a Kramer Confidant shirt/holster in a business casual workplace for a number of years. It worked out very well. I used the full length model so that I could tuck it in, and it worked out great. Some buttons on my shirt would probably have been sacraficed if I had ever had to get it out in a hurry, but I could live with that.
I still carry the Kahr in a Galco pancake style holster, weather permitting. I get hot in stores sometimes when I can't take my jacket off, but it hasn't killed me yet. When I'm going to be working in particularily "sporty" neighborhoods, I carry a Glock 22 in a Fobus paddle, with two spare mags in an offside Fobus paddle rig.
I must admit though, that I have become a HUGE fan of my second generation KelTec P3AT .380 ACP. I installed a belt clip on it, and can carry it strong side IWB with just about any clothing combination. If I'm wearing a belt, the clip goes under the belt to aid in concealment, and to keep the thing from bending and/or gouging up seats, uppolstered or otherwise. With a tucked in shirt, I just untuck it enough to fold over the beltline a bit, and the KelTec disappears. If I absolutely cannot carry it strongside IWB, or if it's being carried in back-up mode (now that weather is beginning to permit carry of larger pistols), my el-cheapo Uncle Mikes pocket holster works great in any pocket. I think that current defensive loads for the .380 come pretty close to many .38 Spc loads, and feel reasonabely well armed with this little .380. I've put several hundred rounds through mine, and after a couple of failure to feeds initially during break-in, I haven't had any problems. The KelTec isn't a Kimber, and it won't win any matches or beauty contests, but for what it is, it excells. And what it is, is a highly concealable, always there, no excuse to be without it, "OH CRAP" belly gun...something to get me either away from a bad situation, or to my car to get the Glock or the Kahr in my grippers.
Sorry, didn't mean to rant, but that's what I think.