The flash and bang will disorient your target much more because they do not know it is coming and adds to the level of violence. It is my firm belief that if someone is trying to violate me or my family I will try to unleash a level of violence on them that they are both unprepared for and never knew existed.
Both carbines and shotguns (barrel and ammunition dependant) register 150-160dbs when fired unsuppressed. This WILL render anyone in the area completely deaf, save some ringing - Tinnitus. The muzzle flash will also temporarily blind and disorient you and your target.