People are saying that having a windscreen cuts down on mileage. Doesn't make sense to me. In terms of resistance, air moving over a smooth surface would seem to be a much better scenario than air hitting your torso. Probably depends more on the size and shape of the windscreen than whether or not you have one.
2005 1300R, 2007 1800T2
Viet Nam Veteran (Medical Corps and Engineering Corps)