All right I will try. Mind that my knowledge comes from mouthpiece manufacture only, and sax body modifications, so I won't claim to be an expert, but this is my experience:
Hard Rubber, ebonite is as close to a neutral acoustic material as you can get. Meaning that the sound waves balance out. The anti waves (lets call them (minus –) and the carry waves (lets call them plus ?)) are almost even.
Materials as Gold, Silver and bronze has a larger + wave, witch our ear and brain percepts as clear and warm. Crystal has the largest + waves - witch is why you can make a crystal glass explode at a certain vibration. This means that + waves all on their own becomes destructive - hence the precens of anti waves - to keep the balance so to speak.
So Gold, silver and bronze are very good materials in terms of acoustics but crystal are the very best. A bit hard to make a saxophone from crystal right?
Iron or steel has more - waves than plus, witch means it kills sound, or you get a kind of retained sound that tends to choke it self..... hard to explain....
Ever wondered why your metal mouthpiece sounds unpleasant in a small room compared to a large concert hall? I think its because the sondwaves are "designed" to carry further in a good mouthpiece.
My humble guess would be, that a stainless steel mouthpiece would sound fine in a small acoustic setting - but disappear in a modern band setting....
