Didn't read everything for now (have to leave for work), but a short note about flute sounds:
In general, the player determines the sound much more than the flute. The funny thing is, that, to my experience*, the longer a player plays a flute, the more it sound's like the player's typical sound. Each flute has a quite unique sound to it that speaks if the player isn't accustomed to the specific needs of the embouchure hole etc.
There are certainly some factors that determine the "natural sound" of the flute (overall embouchure shape [not only general shape, i.e. circle, rectangle etc.!], bore diameter, bore taper, hole size...), but in the end the player makes the flute sound like he/she wants it.
To illustrate this, here are two true stories:
My flute teacher used to own an Aebi Pratten and a Rudall, also made by Tom Aebi. He played the Pratten exclusively until he got the Rudall. After getting used to it and using it in a band rehearsal, the other band members asked him: "Why the heck did you buy that flute? You don't sound any different!" (and all of them are experienced musicians with lots of hearing experience!).
The Pratten is now mine, and I sound like me, not like my teacher, FWIW. The sound has a little less hiss to it than my Reviol, but that's caused by incompatibilities between embouchure design and my lip's design, which one of the few factors that really depends on the flute. My teacher sounds pretty much like on his Aebi when playing the Reviol. Without hiss.
A friend plays an Ormiston Rudall. Nice flute, and the more I play it, the more I like it. It's the same with my Aebi: when she tried this model for the first time, she couldn't play it, and everytime we meet and she tries my flute again, she sounds better. But she doesn't sound like me, she sounds like on her Ormiston which is pretty much the opposite of a Pratten.
* One can find sound samples of my playing in the Posting Clips thread in case one wants to verify my ability to have an own opinion about flute topics.
