I've tried the "Jamar" push the brake pedal down and push the knob and release the pedal kind.
They suck, nice when they are new but after about ten usages they gum up and won't release anymore - so then your stuck out on the trail trying to release your friggen brakes (maybe it was just a VW thing, but brake fluid is brake fluid) The Granger manual valve seems like a worth while try - you got leverage on them.
