A lot of people that produce brushes do one of two things.
They either make the brush to what they think it should be, and sell it as such (e.g. they pick the knot e.g. plug width, socket width and depth) and hope that people buy it (Paladin, Morris and Forndarn w/Lee Sabini, Brad Sears Shaving, Elite Razors, Simpson, Thater etc.).
Or you have those that focus around the knot, and then turn the handle to match (like Shavemac, Envy Shave, Doug Korn, Rudy Vey, Wolf Whiskers, Wilborg Shaving etc.) where they get the knot first, and build the handle around it.
There's a level of trust with the major established guys like Paladin, Rudy Vey, Shavemac etc. where you can tell them the criteria you want out of a brush and trust their advice (e.g. you ask for a dense fan knot, with no scritch/scratch but good splay and backbone). Now, the only way to know what all that means is to see it in action
We'll chat, but I might even try to organise a Brisbane meet up with some of the members and Chrissy drinks?