I have the 13", SERG Cee Baileys. I am 5'10", 31" inseam and sit tall in the saddle. Stock '10 FLRTX seat.
It is ok, not great, for removing buffeting. It looks really good though as I got the dark tinted one.
My buddy has the Klockwerks and he raves about it, but I have ridden his bike and don't see any difference.
I put soft lowers on and installed the deflector in the centre, under the fairing, and that helped.
I have another windshield, stock from an '08, and that is better for controlling the wind around the ears, just doesn't look as good.