The Wunderlich Vario screen works very well for me. It increases the comfort of riding hugely (and looks good, in my opinion). Even in nasty weather conditions, it really does work very well. I bought mine through my local BMW dealer (Balderstones) who fitted it for me, no trouble at all.
Another good feature is that, being variable, I can alter the height in warm weather to get more air flow if needed. Will be very useful when I go abroad, although full height often better in the UK!
I'm exactly 6 foot, and it works great for me.