
I'm wonering what position you have you windscreen in when experiencing buffeting. The only time I ever get even
slight buffeting on my R1100RT is when I have it all the way up, which is very rare. My "big" windscreen is a Parabellum that is 4" wider and 2.5" taller than stock. I also have a smaller (summer) windscreen that is a stock screen cut down 2" on width and 1" on height. It pretty yields the same result on buffeting; only when all the way up. Otherwise, both screens provide smooth air across my face when in "normal" position which is either all the way down or raised just slightly.
If you haven't already done so, you might try experimenting with various positions before discounting the windscreen you have.