I looked at Knopf (and he isn't off the table yet..) but his stable of bikes is really rather limited. Either too big (RT's) or too old/uncomfortable for me (K75C) - and I know people will tell us all about the BBG they did on the K75C (actually John Ryan set many of his records on his old K75T), but the bike just never quite fit me right (THE K75S..) and after about 200 miles I was in awful pain.
The big reason I'm leaning toward an R1200R - (and you probably know the feeling since you own one) - I can get off it after a long ride and still walk around, and I actually look forward to getting back on it in the morning. That wasn't the case with the K75S, despite lots of seat tries, different bars, etc. Just wasn't the right bike for me.