Was any benefit gained by Scott in fitting three ring pistons to their Clubman engines? I know that they were faster, but that was probably down to the type 29 Amal carb (1 1/8″ bore) and the deeper TT transfer port covers plus probably more careful assembly and polished internals.
My opinion is that 3 rings are not necessary
I use 2 on road engines and 1 on competition engines
If they were a bit quicker, it was most likely down to a few gas flow improvements, but this knowlege has progressed since then