To properly outfit a large Department with revolvers, you need to look at the whole job, not just the shooters. I'm a retired guy from the NYPD. The good shooters, who take it seriously will do well with whatever you give them. The reality is that a LARGE percentage will show up at the range twice a year, attain a passing score, then go back to spilling coffee into their holsters until next time. In 1990 when I went on patrol with a 4" NY-1 loaded with 158 grain LSWC's, (pre NYCLAD),and a 2" NY-1 in my belt, I was complaining about not having a 9MM, but never felt I couldn't address anything that came up during the tour. The 64's available in 4" and 3" as a patrol gun allowed a broad range of average shooters to do fairly well on the range as well as on the road.
Give'em K frame's!