Couple of things:
First off, for comparing FJR windshields you definitely have to segregate the first gens from the second gens. The bikes' aeros are different enough to begin with, and then each shield manufacturer has managed to create a completely different model for the each generations (since their mounting is completely different they can't be interchanged anyway). So experience with an MRA Vario, or Rifle, or Cee Bailey on one generation most definitely does NOT translate to the other generation.
Next, when comparing height of 1st gen windshields I find it is most salient to measure from the center screw hole to the upper edge (rather than from the lower edge) as some manufacturers (Rifle for one) will also extend the shield below the screw holes too. Then, you'll also want to note any vertical curvature of the shield (or lack of it) as the convex curvature on the stock Yamaha shield and touring shield has the effect of lowering the upper edge significantly.
For instance, you guys are getting all excited about the MRA Vario which Scott measured at 19.5" (from the lower edge). The Ahamay Touring windshield is 18" from the center screw (add about 1.5" for the screw to the bottom edge) so it would be about the same height. Of course it is convex and it doesn't have the dual layers that generates a smoother air flow off the top, but if one were to stick a Laminar lip on the Ahamay, I'd say they would have a pretty similar shield to the full extended MRA, but it would be less adjustable.
Being 6'2", with relatively short legs (hence a long torso) and sitting up on a Russell seat (+1") I have determined (at considerable expense to myself) that there just isn't a windshield made in the world that it high enough that it will shoot the air up over my head. That "bubble of still air" nirvana is unobtainable for this cowboy.
The best I found is to run the jumbo Rifle Touring (a full 22 1/2" from center screw to top lip, with no vertical curvature) and I still get a riffle of turbulence to the very top of my helmet, unless I duck down. But ducking down is bad back posture and I couldn't ride like that for very long.
However, with that much shield coverage I would roast in the summer. I do know some other folks that are able to keep theirs on all year, but I switch to either an Ahamay Touring or a Stock OEM shield mounted on the Rifle tuning blocks during the warmer months. With the shield mechanism fully lowered it actually scoops air off the front of the faring and blows it down onto my torso behind the dash, and my head is way up into clean air as if the bike had no faring or windshield at all. Of course if it rains we can still "deploy the shields, Captain!" and it still helps some with the weather protection.
