Power drum brakes are actually BETTER than disc brakes in stopping ability since there is much more friction area between the shoes and drums than between disc pads and rotor. Now to qualify this; if a lot of heat is generated like in heavy traffic or hills then the drums have brake fade while discs don't and discs are self cleaning and drying when exposed to dirt or water--in other words all around better brakes. For regular use and not with heavy loads or trailer your power drum brakes will be more than up to the task.

Evan