Yes, the disc setup is heavier, and it's worth every extra ounce. I've had Novas with drums ('69) and Novas with discs ('69 & '72), and there just ain't no comparison. Even with arc-ground semi-metallic shoes and everything else in top notch order, the drums don't hold a candle. Seriously, if you want to be able to stop decently (and in a straight line) from anything over ~60mph, use the discs.
In an extreme drag-racing situation, drums have two advantages: less weight and less drag. But they also have parachutes.