On the other hand, I've got over 40,000 miles on mine without the cooling kit and have never had skip fire kick in.
Incidentally, the fan is set to kick in at low (or zero) speed rather than just being triggered by rising engine temperature. I don't know if temperature alone will actually trigger it.
I'll add that the shrouding that the kit adds behind the engine does provide more even cooling of the cylinders when running at speed than without.
I live on the same glacier as RedThree. I dont have the UKC & in 15k miles never encountered skip fire. So Bluebricked your statement " I actually look to see if the UCK is installed on M3Ws for sale - if it is not installed that tells me the owners never really drove the cars much." is not acurate. It maybe valid wherever you live but not on the glacier. This year my car has moved twice, collecting it from getting lower half repainted & a week later 12 miles to local town. Since then the weather & roads have been to bad to get it down the hill back up again.
