I've used the Brake Smart controller since 06, it is far superior than most other brands. The Max Brake mentioned in a post by dieselengineer works the same as Brake Smart by using brake fluid pressure to sense braking needs. The Brake Smart was over $400 when I bought mine, the Max Brake sells for about $350.
The BrakeSmart enhances these systems because we measure the brake pressure of the tow vehicle then give a signal (voltage) that is proportionate to both this pressure reading and what the trailer is asking for. All of this is independent of pedal travel, vehicle or controller attitude.
Don't go cheap on a controller when you are trying to stop 11 tons +/-.
Forrest