Beringer Disc Brake Kit for Schemm-Hirth gliders - experience and effectiveness?

Has anyone ever got a hydraulic Tost disk brake to work WELL on a Ventus 2CM? I'm convinced I've bled my brakes as well as they can be bled, and STILL the braking is very weak. I get some small braking action, but nowhere near being able to put the glider on its nose, or flat-spot the tire. I can slow down for a taxiway turn off, so long as its well ahead, but not enough to help on a short runway, or enough for a real emergency stop. I suspect the wire cable between the control stick and the cylinder under the seat must be stretching. I may try a thicker cable (I'm experimental).