I've come to use Walter's mouthpieces exclusively on soprano and bass clarinets. Nothing short of extraordinary....right up there in the same league with Gregory Smith and Richard Hawkins.
As I've written on other threads, the first Grabner mouthpiece I used was his LB on bass clarinet. Being deeply impressed with it, I HAD to try his Kaspar-style pieces on soprano. The Grabner Kaspars came as a revelation to me. I mostly use the K14 and K11 models (however, I also have the 442 K11e and K14e versions). They have a truly beautiful dark, warm, vibrant, and ringing sound....exactly as Walter describes them on his site. With a Grabner Kaspar I'm able to have the dark, ringing clarinet sound of my dreams but I also discovered that its a big sound that projects like gang busters. It easily projects in a big band (as well as classical wind ensemble) without breaking a sweat.
Walter has hinted that he might begin a line of saxophone mouthpieces. I told him that I want to be first in line to try one.
Roger