From Left to Right: California Scientific 22" - ZTechnic V-Stream 16" - Skidmarx Double Bubble - Stock ST Screen
First off some disclaimers to point out the obvious:
1) Not every person is the same height
2) Even if two people are the same height, some people have longer legs while others have longer torsos
3) Different seats, rider posture and riser heights effect where a rider's head is positioned in the windstream
4) Different helmets cause different "sound effects"
Ok, so let me give you some specs on myself and my bike to put things in perspective... I'm 5'9", I weigh 170 and have a 30" inseam. My F800ST is equiped with a low seat (which I believe is 1" lower than stock) and the SW Motech risers (increasing handlebar height by 25mm (1.0") and move them back 25mm (1.0"), producing an overall handelbar displacement of 35.4mm (1.4") at a 45 degree angle from the original position.) I typically wear an HJC CL-33 3/4 open face helmet with flip down face shield and on sunny days, Spy Optics Meteor sunglasses.
First off, I'll start off with the stock ST shield. I found it not too loud, but suffered a fair amount of buffeting. I could not ride off above 20mph with the face shield up due to the amount of wind hitting me in the face, getting under my sunglasses, bouncing them around and causing my eyes to tear up.
Next I tried the V-Technic shield - which was on the demo bike that I rode at the dealer. A big drop in the buffeting, but converse to the stock shield, much noisier. If I stood a little on the pegs, it quieted down significantly. Alas, even though buffeting was lessened, the wind was hitting me in just the right way that I was suffering the same issues with trying to ride at speed with the face shield up. With it down, it would sometimes cause loud whistling noises, so I kept it partially cracked.
I won the CalSci screen on EBay for a whopping $26 from A&S Cycles in CA. It arrived yesterday. Lookswise, this makes the bike look like a real tourer. No buffeting at all since it sends the windstream up at my forehead. I was a bit skeptical about what wind would be coming through the two big holes near the bottom, but I can't really feel anything, however I fully expect bug splatter on the back of the controls. I definitely get windnoise where the windstream hits at almost exactly where the helmet and face shield meet, but it's slightly better than stock. If I duck my head down slightly, the noise is almost entirely gone, because at that point, it's going up over the helmet. Obviously with the wind hitting this high up, I can keep my face shield up without my glasses bouncing around or getting teary-eyed. Not much of any wind hits my body which makes this a good cooler weather screen, but fairly stifling with today's 98 degree F and 80% humidity. Coming from a cruiser background, standar wisdom is that a windshield should be about level with your nose and you shouldn't have to look through it. For me, this screen is perfect in that regards.
Today I received the tinted Skidmarx double bubble screen and I was amazed to find that even though it's about the same height in the middle as the stock ST screen, I get less buffeting, about the same noise level, and strangely, I can keep my face shield open and no sunglass wobble or teary-eyes. Not to say that I didn't have a bug or two disintegrate on my face, but that was the only discomfort. Nice airflow for a hot and humid day - especially when you take into account the option for open face shield riding - and it looks great on the bike.
In conclusion, choosing the shields with the least buffeting and noise with the option for open face shield riding, I believe I will be sticking with the Skidmarx screen for hot weather riding and the CalSci screen for cooler weather. Again, YMMV based on your own physical stats and bike setup.