Okay, here goes:
Took it out, this morning, for a test drive.
Only positive things to report, really.
With window openings (mainly driver's window, but checked with both) up to 115mm/4.5": The annoying side gusts on head and face are eliminated. Wind noise is significantly less, even up to Motorway speeds it remains conversationally quiet, which is an improvement.
So the 'four passenger in a rain shower steamed windscreen' clearing ought to be a doddle in comparison.
Harder to nail, and obviously all of this is subjective, but it seemed that the wind noise, at high speed, with the windows closed was also reduced.
I know that, on my Alfa which had deflectors fitted as standard, when removed, at high speed you can see the top of the door lifting away from the seal at high speed.
If I have to include a niggle, the two metal clips which secure the deflector seem to be a touch bigger than they need to be, but that's probably more to do with my hyper-fussy nature.
Four and a half stars from me.
Any further developments and, when I get a chance, photographs (they're not the easiest things to shoot, of these) will follow.
Edited by Quinlan minor, 12 June 2020 - 09:20 AM.