I can still see over the windscreen unltss I raise it to maximum height, then the edge is right in my line of vision, which is very distracting. I found I can run the screen at about the midpoint of the stock adjustment and with the extended brackets, the buffetting is still above my helmet. The lowers virtually eliminated the turbulence that comes up over the tank, but on a hot day (yesterday was +90F) it gets a little uncomfortable. Another thing I noticed after raising the windscreen and adding lowers is that the noise level is reduced to almost nothing.
I had a "Speedster" screen in my previous bike (BW R12C) and hated it - seemed to throw everything right up into my neck/chin area. I am afraid the fly screen would do something similar.