Ah yes, GT windshields. I've tried them all. That includes BMW Tall, Cee Bailey +6 +3, Cee Bailey +2 +2, CalSci Tall, and Aeroflow.
I'd tried the BMW tall windshield on a friend's bike, and knew that it wasn't gonna cut it. In fact, the dealer left it in the factory wrapping as I put on a Cee Bailey before I rode the new bike away.
The Cee Bailey +6 +3 worked much better, but was huge and flexed at speed until it eventually cracked. I rode to Cee Bailey's manufacturing plant to complain in person, and all they had to replace it at the time was a slightly tinted +2 +2. That lasted on the bike less than 5 miles before I pulled it as it was just way too short for me, never mind my poor wife.
I then ordered the CalSci Tall which gave much smoother air, though still some low frequency booming at speed. It still let too much air around the sides for my taste, but those that are used to smaller sport bike shields or mostly ride solo will probably find it just fine.
I've since switched to the full Aeroflow/AeroGard setup. It gives much better protection, even when raised less than the Cee Bailey. And the AeroGards take the wind off your hands and arms and smooth the overall airflow a bit more. It's pricey, but it does work.
I haven't tried the Z-Technik screen, mostly because it wasn't available when I was searching. But the only thing I could see better than the Aeroflow setup that I have now is a K1200RT, which would probably require a new windshield anyway.
The problem with changing windshields is that everybody's different, with different expectations. Getting advice from others helps, but like buying the bike, you really need to try them yourself to see what works best for you.