Sam,
You fail to say where you live: in the hot South West, in the moderate Northwest, Central USA, on the East Coast, etc. All of the police bikes that I have seen on the west coast are also 1200 RT's. However, you NEVER see them in stop and go traffic. I used to live in a large city also. You NEVER see cops sitting in traffic. They are always passing by stopped cars on the way to the accident, or parked on the side of the road giving tickets. They never just sit in traffic. Because of this, they always have air going past their jugs. The last cop's RT I saw here in my town was towed away because it failed. Now, I don't know why it failed, it just had to be carried away.
Sorry about that, I live in Albuquerque New Mexico. In the summer we see many days over 100. The cops that have started riding them, absolutely love them. The city got a cheaper contract for cop bikes through Honda and several officers got a petition together to boycot the new Honda police cruisers because they like their Beemers so much.
As long as you use the BMW recommended synthetic oil and follow the oil change interval, they will last a long time.
My wife has a 1972 R75/5 that runs great in stop and go traffic, and it doesnt even have an oil cooler.
BMW Master technician
BMW S.T.E.P. graduate, 10 years BMW dealership experience