I use them on all of my pieces. They are getting sizes regulated to fit more mouthpieces more precisely.
I have several friends who use them on sax and clarinet and love them.
The sound can manipulated by adjusting the metal bars on the side. Hence, you can brighten or darken the sound by adjusting these as well as adjust the spread and focus of the sound. At first several people, myself included, felt that the sound was very stuffy but that was because we were tightening the ligature way too tight. Once we loosened the ligature about a quarter turn the sound just opened up.
Is it a "brighter " playing ligature than many metal ligatures? No. Is it a huge open sounding ligature? In my opinion and the opinion of others I know who use them, yes. Your setup will determine how this piece works for you - of course.
On my tenor and soprano, the "improvement " was immediately apparent. On alto, I went back and forth for days before I really decided I would take the fuller and richer overall sound of the Silverstein and lose a few upper partials of a few notes I loved using my other ligature. I do think we make these "compromises" with a lot of equipment we use. I love the sweet sound of my Rigotti Golds but also miss some of the spread and buzz of my vamp stamped Lavoz reeds - compromise.
Man if only we could get the best of what we like from everything wrapped into one. Sorry for the vent.
Anyway, that's my two cents worth on the Silverstein Ligature.