lindermant,
I just measured my 3913. The height is 5" and the width at the widest point (the ambi safety) is 1 3/8". The slide is the same thickness as the Kahr and the weight is about the same.
Because of the alloy frame, the 3913 feels top heavy while the Kahr feels much better balanced. The Kahr also sits much lower in my hand. There is about 1 1/8" between the top of the slide and the web of my hand. In the 3913, there is about 1 1/5". That may not sound like a lot but you can really tell when you hold them side by side.
A couple of things that the S&W has going for for a CCW is that it holds one more round than the Kahr and it is a true DA/SA pistol. That means that if you get a dud, all you have to do is pull the trigger and the hammer will have a second strike. On the Kahr, if you pull the trigger and nothing happens, you will have to either fully rack the slide or at least move it back about an inch to reset the striker. In a gunfight situation, I doubt anyone would have the fine motor skills to partially rack the slide without jamming the gun or ejecting the dud. This could be a big deal if you only have one hand free or if split seconds count.