I have a 12-gauge Mossberg 590 'Street Sweeper' with 8+1 capacity. There's no doubt at all that it's capable of major carnage, but it would take a lot of desperation to make me want to use it in the house. Basically, if it was a question of saving my life, or saving my hearing.
One thing about the model I have -- probably the same loading mechanics as yours -- is that the gun can't use those [Only registered and activated users can see links. ]. Other folks here will have some serious thoughts about setting them off inside a house, if you're set on using a shotgun.