Not all "brake boosting" or "brake torquing" is the same. Some of the guys who run really quick will hold the brake and throttle until the car actually builds turbo boost prior to launch. Others, like me, will bring the RPM up under braking but not hold it long enough to actually see boost.
I am not 100% comfortable putting the amount of stress on the driveline that a "boosted" launch creates. Besides, when I have tried it, my glazed worn-out brakes will not hold the car. My best 60 with just a 2000 RPM launch without building boost is 1.89. I know from playing around with my Aeroforce gauge that just an off-idle launch will cost at least 2 tenths on the 60 alone. While slight, there is a hint of turbo lag with an off-idle launch.