Hi Randy, I have 3 sets of the JP brakes, Boomerang MB339, Boomerang Turbinator II, and a turbine converted Freewing F-18c. Mine are the older sets without the pots. They're proportional. However they all suffer from un even brake application which results in a very squirrelly landing and usually dragging a wing tip or nascar slide to stop. My friends Boomerang Sprint had the same tendency to zig zag and usually wound up dragging a wing tip. The work around that we both have had success with is to use a 3 position switch. POS 0 off, POS 1 drag, POS 2 full on. (On radio setup you need to setup in this order. Off, then Full On, then Mid) (kinda like setting up flaps). I'm using a JR 10x with dm9 airmod, He's using s Spektrum GX11,
I also have my elevator mixed to my brake, down applies brake and I use that feature for taxing. My friend copied my set up with the exception he mixed his slider to control brakes for taxi. We fly primarily off asphalt, but sometimes the dry lake bed. stopping is the same for both surfaces.
In landing approach on down wind to base I flip my brakes to POS 2 full on, this magnetically pulls both plates against brake coils, I count to 3 then I set to POS 1 which reduces the magnetic field and reduces braking force to draggy but not locked and then make a normal landing with partial brake applied, and just let it slow to a stop.. Plane lands straight, if more brake is needed I apply down elevator. Because the brake plates are already magnetically in contact plane stays straight.
Hope this helps
Mike