I've heard a lot of traffic on this. One story is the union will fight this tooth and nail, because it's tradition.
I've also heard, in numerous avenues, that a single beacon light on a patrol car tends to draw the drunks towards the light, and is a disadvantage when an officer has a vehicle pulled over.
Also, and it's been awhile since I cruised Detroit at night, but their patrol cars also used to be a single beacon, very similar if not identical to the MSP lights. I wonder what they do with their spares. I've seen them pop up on the CSV courtesy vans lately... I guess to keep them from getting robbed while helping motorists??
There is something to be said about immediately being able to indentify a troop by the light, but it isn't the best light scheme.
and...a little off topic, just how much more obscenely bright are the LED lights going to get before they pull the reins in a bit. I know of a few officers who wont use all their lighting on a dark road, because the contrast between the darkness and sudden bright led's of the patrol car make approaching traffic have a difficult time seeing.