Dear colleagues
In this regard I believe that there is no discussion on the desirability of 
symmetrical rails as it does not stop the asymmetry of the reed, indeed, I think 
it is appropriate to some asymmetry for rasp or scratch in the right side
of the reed when you need to provide the bass notes, from which starts in the 
back to compensate for the appoggiatura of the mouthpiece in your mouth, as 
attached image, generally tending to rely more on that side of grip as these 
instruments.
Fraternally
Silverio