It really depends on the mouthpiece. If you get a mouthpiece at the extreme end of the spectrum, perhaps something with a large baffle, I would agree that it might not work in concert band. But I used Meyer mouthpieces during High School, and used them not just in Jazz band but also in concert band and for Region and All State auditions for concert band. And these days I use my RPC not just for rock and roll and jazz, but also when I play a ballad in church where I need to get really soft.If you get a jazz mouthpiece, DO NOT use it in concert band. Your band director would likely hate you if you used it in concert band.