Update:
I've had a good run now with the Suzuki vario screen,
I get less helmet wobble & turbulence than Givi airflow at motorway speeds but it's noisier than the airflow at 40-60 mph.
I can ride visor up with the airflow at ~70mph, around 50mph and visor up is uncomfortable with the vario.
Both screens become smooth & quiet if I dip down so my eye is level with the top of the screen.
Overall a partial success. I see some kind of hi bred coming along!