I would also say just get a Link (similar) and learn to play it. They don't offer the "frills" of some more expensive mouthpieces, but they're just so flexible that they're hard to beat.
That said, I've tried the Yani metal mouthpiece for tenor and it was...nice. Too nice for my tastes. I was playing a modern Berg at the time (110/2, SS), and my reaction was that the Yani responded a lot like the Berg, but with less "grit" in the sound, probably because its brightness comes from a rollover baffle and a small chamber. It didn't feel like it had the depth or cojones that I think a tenor should have. Of course, a modification like Heath described seems like it would make for a great mouthpiece. I bet they work great on alto in their stock condition, though.