Drizzt,
I have had a Mossberg 590, 12 ga shotgun as my home defense weapon of choice. It has nearly 10,000 rounds through it with zero malfunctions. You have a quality piece for defense, that is for sure. IMO there is really only one thing that a long gun like that needs to fulfill the home defense role and that is a light. Unlike the handgun you can not operate a door and a light and have a free hand when using a long gun. Bearing in mind that most shootings occur in low-light to no light situations a light will be your best friend! Make sure you own the night!! Surefire sells replacement forends with lights attached, which are expensive but worth the money. Then you have Brownells which sells light mounts that hold any light which is 1" in diameter, but then you typically don't get the option of a pressure pad on/off switch. You can also attach a mini-mag lite, and while some swear by them I prefer blinding light rather than something used to check pupils on a field sobriety test. Let's face it, if you are going to shoot at night, you had better be 100% certain what your target is, and that is no time for a wimpy light. So go with something around 65 lumens at least. I would say other than that keep all of the side saddle carriers off of it and bandolier slings and don't go with a pistol grip cuz it hurts, and you'll be all right.