I will speak from my own experience, I bought my first bike (R100RS) when 22 years old. I worked on it, I ran the snot out of it, and epitomized the young punk on a bike. As much as I abused that bike, it never gave me a problem, and it wasn't a tinker toy. It was a tank. In 1999 I bought a R1100R. Within the first year I put over 60K on it, and never did anything other than the directed services. I sold it an bought a more comfortable R1100GS for long distance. It was a used 1999 with 90K on the clock, I sold it in 2005 just before Katrina. When I sold it, I had racked the odometer up to 220K, again nothing more than services every 6K and tires. After Katrina I bought a used R1150GS with 75K on the clock. That was my bike thru 2012, when I bought my S10. I finally sold it with just shy of 200K on it.
That history being told, I never had a final drive issue, tranny issue, or any of the other systemic BMW problems that are always reported on the forums. I think the fan boy base for BMW is well deserved, but most never put any real miles on their bikes. The new model comes out and they have to have it. That being said, the down side to BMW ownership is the cost associated with service.
I guess I am a fan boy, but I ride an S10, and haven't looked back yet. As a side note, my old BMW mechanic Tom High, just got his 1 million mile medallion from BMW. All on his R100RS that he bought new in the early 80's.