I found it hilarious that someone here posted a screen shot of Swedish police carrying sub guns like it was the norm.
Ever been there? I have, maybe 6 times in the last ten years because of visits to relatives, both in Stockholm and a small town in the south.
First, that is a very unusual scene, definitely NOT the norm, they general carry just a sidearm.
Second, Sweden has one of the lowest crime rates in the world, so I can only suspect that was a special occasion.
Third, they are probably one of the best trained police forces on the face of the earth. Their academy is two years long, as opposed to the normal four or six months here.
Posting that picture was like comparing grapes and watermelons.
As to the OP question, like any job, you always do better with the correct or better tool for the job. As a former LEO, I would consider the semi auto the better tool, thus obsoleting the revolver. Not to say they won’t work, but why not use the better tool?
Points that lead me to that conclusion are increased capacity, ease of reloading, and better fixed sights.
I was thrilled to replace my 5 shot Chief with an 11 shot G26.
Re: emulating the FBI, many small depts. don’t have the funds for their own R&D section, so they follow the agency that has the best regarded one.
My smaller agency in NYC, 3500 officers, follows the lead of the NYPD, 30,000 officers. We went straight to 9mm Glocks from .38Spl. revolvers.