Impaler, I just installed the Yamaha 19" windshield. I'm 6'2" and it's not working so well for me. At higher speeds the windstream strikes the upper half of my helmet and the resulting turbulence is like having my head attached to one of those paint-can mixers they use at Home Depot. I resort to bending down to look through the shield which is a little pointless. I believe my eyes are about 3-4" above the top, but that's just eyeballing it.
I am 6'3" and I have the OEM 19"er. My eyes are 3-4 inches above the top and I get just the right amount of wind on myface/head/helmet. I wear a shorty half helmet with 7-eye goggles. I love it and I like that it doesn't take away from the lines or angle of rake. A+ from me.
Should also state, that I rarely use the shield...mostly when I decide to ride into the city to work. Evenings, night outs and weekend cruising is sans windshield