I have a Colt Mustang. It is no longer in production but is widely available on the used gun market. Prices seem a little high in my opinion.
It is a small .380 that is very similar to a 1911, but with no grip safety. It's a nice little gun and at close range shoots a nice group very quickly, but I have two gripes with it as a carry gun.
1. I don't trust .380 to stop a fight, I don't doubt it'll kill someone and I know the european cops carried them for years, but I just don't think it's enough to be trustworthy at stopping a fight-I think .380 falls into the "better than nothing" category like .32 and .25. I prefer at least a .38 special or 9mm
2. The Mustang is single action, so you either have to carry it cocked and locked in a pocket holster (which I think it was what you would have to end up doing and I have tested it empty with a Don Hume pocket holster and couldn't get it to accidently go off) or you have to work the action before using it. Colt also made a double action of the same pistol called the Pony, I believe. Either gun would be better in the airweight, or whatever they call the aluminum frame model. My steel one pulls on my pants too much. There is supposedly an excellent pistolsmith that works on Mustangs and Ponys, but I can never remember the name, except that he's scottish.
I don't have any experience with the Colt Pocket Nine, but I'd be tempted to gamble on one and see how it works if it's small enough for you to comfortable carry it.