Pennsylvania is a "shall issue" state, with several hundred thousand concealed-carry-permit holders. Some large number of CCW-holders work in Philadelphia, and carry there. Downtown Philly, while not as crowded as mid-Manhatten at rush hour, is still a high-density urban area. We have not had any incidents that I know of regarding a CCW holder firing wildly and hitting innocent bystanders. Same deal with Pittsburg. Florida is another state with "shall-issue" CCW, and I've not seen any reports of innocents being shot in downtown Miami, Tampa, Orlando, Ft Lauderdale, or other major areas. Considering how anti-gun the press is, I'm sure I would have heard (over and over) if any such incidents had occurred.
CCW holders tend to be MORE serious about being trained, given the potential liability, than the average cop does. From talking to people who train cops, and supervise their yearly qualifier shoots at the range (a cop must demonstrate he can hit the target once per year), the average cop tends to not spend much time practicing on the range and tends to be an inaccurate shot.
Did you know that the population of the City of New York is greater than the combined populations of Philadelphia, Miami, Tampa, Orlando, and Ft. Lauderdale? What works in otherplaces may not be practical in New York City.