I just got mine installed in the last two weeks, so not too much experience yet in really hot weather. I am 6'3" and went with the stock shape 22" screen. The additional protection is really nice. At first, with the face shield closed, I found it too hot. It was low humidity in the high 80s. But, I actually found it nice to ride with my face shield up using sun glasses. You get enough protection that it is comfortable and significantly cooler. When going past 65 mph, I was putting the face shield down to cut out noise but left it slightly open for the air. I think it is a compromise but I prefer the extra protection and the option to open and close the face shield vs. getting blasted all the time, even at mid speeds. At 6'3", our heads just stick too far up for the stock screen.
I did play with the angle and heights, but kept dealing with the buffeting issue. Their recommended setting, after tweaking it about a half dozen times, is where I ended up. What a surprise...
Also, before getting the Madstad windscreen, I had added the side deflectors, and they made good progress in reducing the buffeting, so something to consider.