I have used the Dart Flyscreen on my Honda CB1100 for close to seven years. I found it improved the airflow to make a pressure wave, for me, at upper chest high with my helmet in clean air. Turbulence and wind pressure was reduce from standard. A side benefit is that the instrument cluster stays bug free.
The original screen was light tint but suffering from over a 120,000kms of bugs, birds and the occasional stone. I have re-ordered, and promptly received a new screen, this time dark tint...