No problems on my Ultra. I have a 13" LRS Mako and thats about it. Lowers help I'm sure. Tons of discussions of windshields on roadglide.org. I do hear that some passengers complain on RGs
Just swapped last year from a batwing to a RGU, won't go back. I do not see as much buffeting as when I had the Road King or added the fairing to the King or when I rented Ultras over vacations, don't catch a lot of turbulence behind semi's or when riding in crosswinds, do not have a need to add a fork baffle or a set of side fork deflectors or extra side wings, the front end seems more stable not having the shield catching air and directing energy to the triple tree. As to air on me, there are two paddle shaped deflectors that mount to the front crash bars and direct the air from the attachment hole over my head, I did feel considerable buffeting air at my eyebrow line with the OE w/s but I am 6'2" with a longer torso than most so I a head above most, the wife noticed some excess air buffet just at her helmet line and a Windvest turnup w/s cured both.
During a test ride, I noticed similar buffeting, but it was w/the low (black) w/s. Just like your FLHX, if you stick w/the stock-short shield...it'll shake your eyeballs out @ anything 50+. Have you tried a taller shield yet?