I just did a lot of research into the very same question and I narrowed it down to either a Kahr 9mm PM9 or a Sig P239.
I realized that while the Kahr is a fine, thin, light pistol, it wasn't worth, to me, the money they're asking. And I could have picked one up new for $500.00 give a little either way.
I bought a Sig P239 in 357 Sig and this pistol is really special. You could easily get this in 9mm or .40 but I wanted the newer cartridge for CCW.
First time out, 150 rounds of FMJ and 20 of Speer Gold Dot 125's and it ran flawless. Hardly any recoil, and a little muzzle flash but nothing bad. I've heard the 9mm is a smooth shooter like a cream puff so if you want something like that, the 9mm would float your boat.
There is NO comparision between a Kahr and a Sig though there is a weight difference. However, with a Milt Sparks VM-2 or similar IWB, there's not too much to worry about re: additional weight.
Good luck.