Considering BMW, seeking advice

As a long time japanese-style bike rider I love the smoothness of an inline 4 cylinder but I want shaft drive so the options for those are very limited where I live. So I'm considering a used R1200RT, R1250 RT, or a K1600 Bagger. But before I buy I wanted to ask owners of these models what they think of them and if anything I'm wondering holds any truth. I realize reddit may not be the best place for this type of feedback but I'll try all options. My concerns are as follows:

• The vibration (or lack of smoothness) of an opposed twin engine and how it feels on the body on long trips

• the complexity of the variable valve timing in the 1250 models and their reliability

• the overall complexity of the k1600 engine and the associated level of effort to perform basic maintenance myself as well as cost of dealer service on an engine like that

I'm mechanically inclined enough to do oil changes, air filters, removing wheels, but that's about it. Previously I've owned a Kawi Concours, Hayabusa, and some smaller sportbikes. Appreciate the input from those who've owned BMWs like the 1200 and 1250s.

Cheers.