Well I have an R1100GS, and have taken both of the last two models of GSA for a test ride, and whilst the were both fantastic bikes, my problem was that, I have the TT tank on the 11, wilbers suspension, corbin seats, after market exhaust and ricky bars.
I left the test drive thinking that neither handled that much better, neither were that much more comfortable (in fact less) all three go as fast as I want to go, I just didnt get that "this is so much better" that I have to get one feel. I couldn't find £12,000 worth of difference let alone £12,000 better than that which I was already riding.
So I got a 990 adventure as well as not instead of as it is a completly different ride. Although I do fancy a S1000Xr and another "as well as bike"