yes thats true but who wants to drive with eyes sticked on temp needle ?
And you know that with some passengers in car, music etc you are not able to watch temp needle always.
Other thing is that temp needle will go into red in few seconds and that few seconds can kill your engine because few seconds in red light = thousand of dollares.
I know what im saying. I had one engine swapped. And why ? I was trying to park my car between 2 cars when my viscous clutch failed. I had my head turned on rear glass when trying to park correctly and when i turned my head to front, i saw white steam.
Electric fan can fail anytime because its fact. And imagine that you are driving in city with 38C outside, talkin with friend and you didnt notice needle in red.
All you wrote about mechanical fan is true but fact that its more reliable in term of cooling is proven by bmw mechanics. I want to do swap to electrical too but im just thikning and asking myself what if ...
I know that mechanical fan can damage some other things but mechanical fan will fail when clutch is engaged and you spin your engine to 6500rpm. And when cluthc fail, you can hear it. When you hear it = its time to replace clutch.