Here is my VStream in its latest setup. Notice that my handlebars are now rised by about 1.5" or so with risers, which gives me more space forward and the shield is higher. At 6'4" I can hide behind it with a slight lean forward. I had it in a slightly higher position, where it hides me completely without ducking at all. There is a slight buffeting, mainly because the top is a bit floppy, I think - even if I duck entirely behind it I can feel it. With a solid bottom mount it will improve a bit more in terms of being more table and less floppy.
I like it though, since now I am pretty well protected from the wind, including my shoulders and head. There is some back-draft, not much though, and I think I prefer that vs. leaving too much space under the screen (which I tried and there is too much air movement at my chest then, so now it is better).
EDIT: I think if eventually I get to make/install a fairing on the SR, this type of windscreen will work well with that. What I don't like now, with a handlebar mount, is that wind-caused vibrations transfer to my handlebars. Without a screen, the ride is smoother at the handlebars. That is at high speeds though, above 50mph, where if I don't have a windscreen I have worse problems by being blasted, so this huge screen is still better on balance, especially in cold weather. I much prefer without it, in terms of being able to duck forward and get my chin near my handlebars for turns balancing on the side of the bike - the large screen kind of interferes with an aggressive forward lean/hang off the bike...