I don't know a whole lot about them, but I do know that they are not mass produced. They are custom made, from what I understand. The local shop I go to sells them, and swears by them. They are not cheap, but they are made to very tight tolerances. I am currently shooting a Copper John, and its okay, but I am definitely going to something that micro adjustable. Just my 2 cents.
You can check out their website at Waltons Glen Archery