Sorry, I just couldn't resist the pun. I am a rank beginner and it probably doesn't really make any difference for me, but I am curious and I really do want to learn as much as I can about clarinets, so does it really make any difference and if so, what is that difference that the shape of the bore of a mouthpiece makes? I see some, older mouthpieces like the HS* table that were manufactured with oval bores through them. Does this really make a difference and if so what is that difference, or is this just so much marketing hype? Are current production mouthpieces made this way? Are there round or rectangular or rhombic bores?