Agree - it's almost impossible to miss and the shot doesn't kill a sleeping child three rooms down. Shoot a pistol and the shot goes right through layers of drywall - not so with a shotgun. Also, the intimidation factor - anyone looking down the barrel knows you're not going to miss...
Looking down the barrel? Hell, most burglars will be gone about 2 seconds after they hear the round jacked into the chamber. That's one of those sounds you definitely never want to hear behind you.
I've been looking at a Mossberg 500 "Tactical Cruiser" 6 shot 12 ga, 18 1/2" barrel, pistol grip. Big punch in a relatively small package and lots of intimidation factor - it just looks mean. http://www.mossberg.com/images/Mossberg_Guns/930/NEW/54125.jpg
Of course, the standard Glock G17 (9mm) gives you a lot of rounds in the mag... If the original poster can afford it, he should get both a pistol and a shotgun, for increased tactical options. A knife makes a good weapon of last resort too. Not that I'm paranoid - I just like to be prepared... I'd rather give an after-action report than an excuse.