By far most alto players play on hard rubber pieces. This is because they have a warmth that metal doesn't. When you use a metal piece on Alto the tone will be very bright. But if you are looking for a bright smooth jazz sound (Dave Koz) this could be what you are looking for. I prefer rubber pieces because they always seem to have more rich qualities than the metals. I suggest you try out a few hard rubber and metal pieces to see what I mean. Good luck.

Tenor is a bigger instrument and has room for the added brightness. Sometimes I put my old C* on my tenor and it sounds so quiet. Alto is voiced higher and the added brightness isn't needed. It's like EQ on a singers voice. You go with the frequency that enhances the voice most. I DO have an old selmer metal classic mouthpiece. This is the model Fred Hemke was using when I studied with him. It is great for something like Baker Street where the high notes need edge, but not tinniness. Physical size and voicing is what caused the demise of the C melody horn. It just doesn't have a good sound. Fred told me that the new selmer metals are not the same. If you can find an old classic, go for it. I use selmer c*. selmer metal, oringinal meyer 5, and richie cole meyer model. Good luck to you :) Terry