Thinkin about S&W M19 for CC?

[Mr. 16 gauge]

If you are familiar with it, then I say carry it. The only problem that I can see is you might have trouble finding a 'concealable' holster for that 4" barrel. As far as a semiauto being "better" than a revolver, I think that is a crock! I feel just as well armed when carrying a Colt Detective special and a couple of Bianchi speed strips.
My Uncle had a M19 as his service revolver when he was on the sheriffs department; it was the first handgun I ever shot.
As far as statistics go, I think I read somewhere that most gunfights are over (intruder dead or flees) in something like 2.3 shots, IIRC.
Good luck with your CCW course!