Steven, I just purchased an SM3.5
...and thought I would drop you a line with my impression of it - FABULOUS!!!
I began playing euph in high school many many many years ago. I had a Besson 3 valve and used a Bach 6-1/2AL mouthpiece that I played trombone with. I continued with this mouthpiece through college where my major instrument was euph. I upgraded my instrument, but not my mouthpiece. At the time I also played bass trombone with a Bach 3G. For many years I played trombone in a church orchestra, using the 6-1/2 & the 3G as I was switching between 1st and bass trombone constantly. I did not return to the euphonium (my greatest love) until about 4 years ago. I play in a community band now along with my church work. I went back to the 6-1/2 and at the same time stopped playing trombone completely. I wasn't satisfied with the tone or response I was getting in band, as the music covers a broad range of styles and upper and lower registers. I began using the 3G, and was pleased with the tone, but the response and the upper register where not to my liking. I did a lot of research on mouthpieces and what individual top players were using. I decided to try the SM3.5. I got it this past Saturday and only got to play about 15 minutes. Last night (Monday) was our band rehearsal and I always get a good workout there. The first piece we ran through was Holst Second Suite in F. Since I am the only euph in the band, I get all the solos, solis, divisi, and anything else in the parts. I had been having trouble with the high F and G on the solo in the first movement. Last night I soared right through them. What a wonderful experience. The response if great, tone is so much better, and articulations are far easier. I congratulate you and Denis Wicke on developing a truly great mouthpiece, and especially one the is so well matched to the Besson euphoniums.