In close to ten years of pocket carry (with a good holster, natch!
), I've carried--in order--S&W 442, K-T P11, PF9 and currently an S&W 49.
As pointed out, a good holster is essential, as are trousers loose enough to allow access to the gun, yet not so loose it falls out. Besides year-round consistency of carry (so you're not groping around trying to find the blasted gun!
), pocket carry allows you to grip the gun without brandishing, appearing threatening or giving away your element of surprise.