[PHmasterT]

I found an interesting article about this:
http://www.csmonitor.com/1983/0316/031646.html

The late Mr. Deveau claimed that his scale would allow a player to hit each note and stay in tune without lipping.
He stated that the headjoint was the most important part of his flutes and thus were special tapered in a process that could take 3 1/2 hours - while other companies used to take 2-3 minutes.
Also according to him, Japanese flute companies sent their employees on tours of the Haynes company to "spy" the headjoint process.

One thing I could notice at first glance is the hole diameter of the open-hole keys, which seem to be larger than the conventional (a bit like Ed Almeida's flutes).