Have you considered this Simon... perhaps all of this pellet testing you're doing is the reason you're reporting that your gun takes less wind?
In theory if an air stripper could help to stabilise the pellet in flight (reduce wobble) then it might reduce the effects of precession in both the horizontal and vertical plane. If you reduce the effects of precession you will have a more ballistically streamlined flightpath, the pellets won't be slowed down as quickly, will spend less time in the air and as a result will spend less time being affected by a crosswind. In theory the effects of precession could be different in the horizontal plane to the vertical plane, which would mean that in the horizontal plane as the pellet wobbles and automatically stabilises it 'might' have uneven drag on one side to the other - which would mean it veers off course to the left or right more.
So if you could reduce horizontal precession then the pellet won't veer off course to the left or right as much as a less stable pellet, which would give the impression that is wasn't taking as much wind.
But... isn't that exactly what you're doing when you test batches of pellets? A pellet that groups well at distance is the byproduct it being more stable in flight and more stable in flight means it will travel faster and spend less time being affected by a crosswind. It may also have an effect on precession in the horizontal plane too - meaning it veers off course less.
Now I'm not saying I don't believe your claims with the mega airstripper, so assuming your observations aren't a figment of your imagination or a case of the Emperors new clothes (If you've spent £180 on an airstripper you want to convince yourself it was worth it right?) then it's possible in theory that part of the reduction in windage is down to the air stripper and part of it is down to exhaustive pellet batch testing. Or it may even be that most of it is down to pellet testing?
Put a chrono out at 50m and try good batches of pellets and bad batches of pellets. In theory you should see that the good batches of pellets have a higher velocity (although it might only be slight) and you should also see that the fps spread is smaller.
You could also do the same with and without the airstripper to see if you get the same result.
If the chrono at 50m test supports this theory, then you'll also have found a quick way to test batches of pellets and you can do it when the wind is too variable to shoot good groups too.
Just a thought....