Only Experience I had with one was on my m1000. We had it on the dyno and by turning the blade just alittle bit actually made quite a bit of difference in hp. Switched it back to what we ran earlier and the hp number came back. It was fun to see what differences it made by turning the blade in different directions. the adjustable is nice to have.
My d&d cans had that last year, never noticed any difference when i adjusted it. I hope they they have a thickertop plate this year, both of mine cracked on the top around 500 miles.