Disc brakes require a lot more leg power to affect a stop than do drums. This is because drums are self energizing. Personally, I would not own an A-body disc brake car without a booster.
This is only true if your system is improperly set up. A system with the proper master cylinder bore diameter and pedal ratio will require minimal effort to stop with no booster. My Valiant with manual Wilwoods stops on a dime and feels like power brakes. I have a friend that runs a road race car at 160+ mph with manual 6-piston Wilwoods and it stops faster than virtually any street car will with minimal effort.
