Here's what the Zagar Sax Mouthpieces site has to say about their current bronze alto piece: "Unicrystal Resonance Technology (URT) creates a unique Baffle-free mouthpiece that outperforms all conventional designs. A highly resonant mouthpiece with a precise response over all registers. This excellent mouthpiece delivers smooth equal power with perfect intonation over the whole range of the instrument. In particular, the mid-range notes (D, D# and E) are brilliant, resonant and free-blowing. Zagar's unique Unicrystal Resonance Technology - brilliance and response is supreme."
Without any bias against the mouthpiece maker, I find the quoted text non-credible. First of all, it's loaded with superlatives that are either empty, subjective, or impossible to verify: unique, outperforms all, excellent, perfect, brilliant/brilliance.
Secondly, the text contains phrases seemingly selected to push sax players' hot-buttons: precise response, smooth equal power, resonant and free-blowing. If there's truth to these attributes, it needs substantiation in plausible detail, without hype.
Thirdly, what exactly is resonating -- the mouthpiece, or the air? Why would making an entire mouthpiece out of a single metallic crystal have any bearing on sax tone? We've all seen claims about unicrystalline copper in electrical wire used for audio applications, but how would this apply to vibrations in air?
I believe those who say that the mouthpiece does not vibrate -- at least not audibly in the frequency range of music -- and that therefore, claims about the sonic superiority of this material or that must be bogus.
With that said, I also believe that the choice of material & method of manufacture can influence both the shape of the air passage within the mouthpiece and the feel of the piece in the player's mouth, thus affecting tone.
I'm neither a metallurgist nor an engineer. I'm just a sax player with an interest in musical tools, their design & their history. I want credible information from the real world; verifiable facts, not hyped-up, mystical lingo. When Zagar's official mouthpiece descriptions start crediting the reader with intelligence & common sense, I'll start taking an interest in their mouthpieces.
And here's a plea to mouthpiece makers in general -- not all of you, just the guilty ones; please stop telling me how some micro-layer of plating provides "focus" or "purity" or whatever. If you plated the piece to mitigate corrosion, or to make it look prettier, or to justify increasing the price, just say so! We potential mouthpiece purchasers will appreciate the honesty.