I have both OEM shields , Calsci XL Wide & National Cycle Vstream and my favorite is the Vstream. Calsci makes a weird airflow combo with my Shoei RF1200 helmet at 6'1. I have to run it max height to reduce the turbulence noise. Could be more of the helmet though sense webbikeworld did state the RF1200 helmet was noisy with windshields, maybe I should of bought the GT-air. Calsci is great for winter time though, covers my hands really well. Thinking I might sell it if my SSD performance hand guards work well with my Vstream. I also like what I saw in the demo video showing the strength of the National Cycle windshields. And looks wise my preference still is the Vstream over Calsci, being in my mid 30's the Calsci gives it almost a grandpa(no offense to the "wiser" members
) look. But sense I care more about function this was never an issue when I ran the Calsci all winter and really enjoyed it. Like the OP I don't have a perfect wind reduction with it but it works the best out of the 4. I think an ultra tall would be my only option for silent air pocket riding.
VStream gets my vote followed by the OEM small for summer. Crazy how much quieter it is with free air flow of the lowered OEM on my helmet.. and cooler.