Giufreddi qualifies as "alot"? Upstream and downstream are very misunderstood concepts and every time they are brought up we get all of the myths surrounding them. I don't lioke to address this because it causes great amounts of cyberchondria. It is sufficient to say that the geometry of the face, jaw, tongue and teeth have a lot to say whether upstream or downstream make sense. There are also not so many teachers that can really help with this so there probably is not enough diagnosis going on. The self diagnosis stuff posted here in many cases is so ridiculous that the informed don't even comment. The practice requirements are identical. I have had a handful of students that have wiped out their playing by switching without turning the brain on first. At least they are not asking about high notes anymore................. I was not able to get them all playing well again.