I fitted a Powerbronze Touring screen at lunchtime and went for a ride after work. Only out for about 30 miles including 18 motorway. I'd say up to 90mph (allegedly) the benefit around the head and in noise reduction is noticeable - I'd say approx. 15% better between 50-70mph, then starts to tail off. From 90 it is slightly improved, but enough to make a difference over a days riding I should imagine. Maybe 5% better. Strangely, I was more aware of wind against the edges of my chest, but that doesn't bother me. I've got spacers to fit too so not finished testing, but quite happy with the screen.
You should find with the extra wind flow created around the spacers the less buffering you’ll experience, from my experience!
