Falc...No I have not personally rode one.However I have seen one ridden extremely well and did not strike me as being something that was overly lacking in go!
My comments on it are relative comments based on the rest of the Beemer range.
I have toughn read comparo tests that featured the GS and they did not rate it as highly as one or two people have indicated. I am not slagging it,I just dont really think it would ever be my choice.