I test drove the XR and also sat on the R.
The latter has sportier ergonomics, a bit like a Ducati Monster.
Suffering from back and neck problems, my choice would clearly be the XR.
It offers you weather protection, an ergonomically suiting riding position and the same power.
The only thing missing in both bikes is electronic suspension for the front, but I didn't really miss that during my test drive, to be quite honest.
As always with BMW, you'll pay a lot to have all the gadgetry, but looking back to buying my XR, I'm glad I got all the extra's, because they are worth it.
All the best,