While I don't have a MS batwing, I have a Harley fairing on my 900 with just a 5" wind screen. I still feel wind on my upper torso but it's not pounding my chest like it did without it. No buffeting either. The only problem I have with the fairing is crosswinds do NOT like a fairing on a bike this light!I actually hated it.
I liked how it took the wind pressure off my chest but I didn't like how it basically made it so I didn't feel any sort of wind on my chest. On other bikes that I have ridden, they had fairings and made it so there wasn't a huge amount of pressure on my chest but you at least got some air to cool you down.
I also had severe buffeting with my full face helmet. The wind came up off the top of the windscreen and hit me right in the forehead of my helmet. My head was basically vibrating down the highway so it made my vision blurry.
Memphis Shades could improve this batwing design immensely if they added some sort of vent system below the wind screen. This would probably help keep the rider cooler if they wanted it while also helping to control the vast contrast between air pressures.
I am 5'9" with a 32" in seam. There are people of similar build as me that didn't have this issue. It might just be me too.