When I transitioned from a revolver to semi-autos, the 69 series had just come out and was the preference of the detectives and office personnel. The street guys went for the full sized 59 series if they chose an S&W. They were reasonably accurate and I did not hear of any functioning problems with them. I had a 659 but did not like it, it did not fit my hand well and my shooting correspondingly suffered. I shot the 69s a fair bit and they were much the same. Our range sargeant shot rings around me with my own gun so I know the problem was with me. I've toyed with getting one of these guns again as police turn ins can be found very reasonable but I am still a bit shy due to past experience. I'm afraid I will find it to be much like my feelings towards the Glock, I like them but they don't like me. It should work out well as a carry piece though I am leaning more towards the single stack 39s in this brand as I know how the double stacks fit. Now if I could only find one at the right price.
UD, I have had a 639 since they came out many years ago. Before that I had a 39. I let a friend talk me out of the 39 and I wish I hadn't. When I saw S&W had come out with the 639 I had to have one. This is a good shooting pistol and carrys well too. I can carry it in my shoulder holster under my dress coat and you wouldn't know I had it on. Works well when I have to dress up. Try one I think you will like it.