I have the Dart on my DS and wear a Touratech Adventure Mod with peak most days, or my Kabuto Ibuki. I can definitely feel less wind on the chest- it now hits me about neck level (I'm 6'2"). The bigger benefit is that the wind coming up and into me is clean and directed. I was getting a lot of shaky air and buffeting off the bow before the small screen was added. I'd buy it again in a heartbeat.
I had the Dart screen, nice but not very protective, since I'm 6"4.
I tried the Touratech screen, which I thought would be much bigger, but when it arrived, I was a bit surprised by its size, I expected more.
With my Mustang seat, the air flow comes a bit uneven into my face.
I'm waiting to test it with my Sargent seat, which is supposed to be 2" higher than stock, the wind should come right below my face, still being well protected on the chest and shoulders.