I´ve a windshield similar than the Parabellum 24 inch, my windshield is 23 inch.
Pro
I´m 6 ft tall, my windshield works perfectly to protect to me of bugs (insects) in the high position, the helmet looks clean after a lot of miles. I don´t have presure over my chest.
Cons
Is a bit noisy (using a Shoei RF1000 helmet) and the worst problem is the fog inside visor using an antifog original sistem in cold weather, for this reason is not confortable wearing glasses. The other think I need to put atention is when a ride in unpaved roads, if is in the high position I can´t ride seated because the top line of the windshield disturb to see, for this reason when I ride in unpaved roads i put the winshield in the low position. Of course in stoned roads with many many stones I ride stand up and the windshield is not a problem to see
Then I think is important to find a correct windshield you must evaluate, rider tall and some other things (angle, support, width)