Z3 Windscreen does it really work

Does the BMW mesh windscreen that fits between the rollbars really work? Is there any other device that works better?

I can only comment on my own experience - not the general category. I have a 2001 Z-3 and almost always wear a hat. The Z was reasonably wind quiet stock. But I liked the wind screen idea and thought I would try it out. First I cut out a cardboard shape like the plexiglas windscreen I had observed on another Z-3. Tried it out and found the wind pressure is on the back side so a wind screen does not add drag at rational speeds. I cut out a Lexan Windscreen in my little shop and fastoned it to the roll bars with Black Velcro. Works very well. I can wear my hat with a full brim up to about 50MPH and I can wear my leather cap up to about 85MPH. Both are significant improvements to no screen. Warning though - there is no magic. Cross winds are not affected. Either environmental cross winds or 18-wheelers can create enough cross wind to remove has with or without the screen