In my first incarnation as a BAR (early nineties), I built and flew one. Two-stage flights at first and they all went wonderfully. Back then I still had the "as big a motor as possible" thing going on. A hang-over from my first foray (when I was much younger) into the world of rocketry. Of course, the first time I flew it with all three stages, I maxed it out, motor-wise.
All ignited—the second stage came back fried (hung for a bit) and the sustainer flew out of sight. Didn't see it again until the next Spring when I saw it hanging about fourty feet up in a cedar tree a quarter mile from the launch site.
A cool rocket and quite attactive and impressive when built. Flew great for as long as I had it.