Good to see you guys having some fun with this thread.
Before you guys get too OT though I thought I would answer the clearance questions with the 10mm and 12mm offset. There should be no problem on the R1100S with the standard headers. I think the HP2S mainly had a problem because the headers came together directly behind the front wheel. There is plenty of room on the R1100S.
Here are a couple quick pics I took this morning of the bike with the 10mm offset.
Markus, thanks for the great observations on your experience with the 10mm offset. Very spot on. Also, there was a thread I posted here years ago about the exact ball and spring replacement sizes for the stock front shock damping knob. Here is the link to that post,
http://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/173134-front-shock-parts-question.html#post1418467