I have kind of gone the other direction. I have been to lots of training and carried and used shotguns for 30 years and seen people shot with buckshot, birdshot and slugs. Within its limitations a good 12 gauge with full power 00 buck with a man that knows how to run it will absolutely dominate a pistol range gunfight. With any kind of shot the max effective range is 15 yards, yes there have been freak occurrences of the innocent getting hit down the road with a pellet and being killed. Lets not delude ourselves,
A shotgun is a close range weapon. For HD as a "repelling boarders" weapon it is great. For clearing a house a handgun is better. For small people a carbine may be better or for all around use a carbine may be better.