I have seen way to many people say this and I'd like to settle it. I did a blind test, eyes closed, ears covered and all, and reversed lead pipe SOUNDS freer, which is why I covered my ears, but isn't, or it isn't negligible. As Ivan said the bracing is further from the bell making it unstable. This instability means that it vibrates more, the sound travels more back to the player with standard lead. The sound travels more outward, not as much forward. However I will see many a poster argue with me. If I remember rightly, Rowuk believes something similar to that too. He is a lot more educated in this matter than I am, well many matters but he may be able to give better info on it.