+1 on the MRA Screen.
I did about 250 miles at the weekend and after also trying variable positions with the sploier - ended up leaving it full tilt.
I'm 5'10" and tested the screen up to 120mph (on a private road obviously

) and found it to to be far quieter than alternative offerings.
I tested the air flow as best I could at usual motorway speeds by putting my left hand above my Tour-X until and feeling for the 'air stream' which seemed to be only just clipping the peak on my lid and then about 2-3 inches clear of the crown.
It's the reduction in noise which does it for me - coupled with having the facility to adjust the spoiler in warmer conditions for a bit of cooling.
My screen quest is also over

- at last