Yes, don't bother taking any advice on screens.
Case 1, F650GS 6 ft 1" rider, found std screen a bit too low, bought a Givi screen, rubbish for him, too much noise and buffeting. Bought a BMW touring screen which he finds just OK. £300 approx before happy.
Case 2, F800GS 6ft 1" rider, happy generally with std screen,he bought a new BMW helmet and things became very noisy, he bought a Touratech touring screen thinking it would be the solution, £165 wasted, noisy, buffeting, generally uncomfy and a waste of money, now back to standard.
Case 3, me, F800GS 6ft 1" happy with the std screen until I bought a new Shark helmet, noisy but no buffeting. I had a ride on my wifes F650 with std screen and it was silent. Fitted the low screen to my F800 and it was worse then ever (Higher bars and position of mirrors?????). Tried the Givi and also no better on noise but with buffeting . I have put the std one back on and now use good ear plugs.
Every rider sits different, has a different helmet and riding style, It could cost hundreds of pounds to find one which works for you. Probably an adjustable spoiler may be the best solution.