I've got the Wunderlich Marathon which is excellent. Standard GS though, not GSA. It's expensive (bought mine second hand) and huge, but I have found it great. I suffered with the original screen at first, bought this very quickly and it's been on my bike for nearly 4 years. Very rare to get any buffeting, only specific wind and lorry conditions on the motorway cause me to feel buffeting, but like I said, very rare. My wife has never complained.
You would probably need the re-inforcement package, which I also heartily recommend, makes the screen very solid.