Mujitsu and Tairaku's Shakuhachi BBQ

I have been experimenting with mouthpiece designs for a while, and some do seem to work 'better' than others. There seem to be some angles that allow for greater expression and volume. While there is much variation around the optimal angles, are there some basic parameters that you folk would recommend as most effective? Perhaps optimal angles change as flutes lengthen and broaden...

Hoping to hear some different viewpoints.

Thanks

John