Tip:
When making considerations on a primary home defense tool, the options are much more varied than for concealed carry. The size and weight restrictions are minimized, leaving us with more viable choices.
Effective vs Efficient:
When considering what firearm to use for home defense, understand that the ballistics of a long gun is a far superior to the handgun. The trade off is weight, length and maneuverability. If you consider that a standard 12 gauge shell carries what amounts to 9-9mm slugs with every press of the trigger. The carbine is much more effective and has the ability to be more precise in a defensive situation.
One issue with the long gun for home defense is that it is not as easy to work around the corners and furniture as a handgun. It requires practice and training to become truly efficient at working a long gun inside a structure.
The second issue is the ability to have a hand free and still being able to work the gun simultaneously. With a handgun, you can pick up a small child and still have the firearm ready to work. The same comes to working a telephone.
If you choose the more effective tool, make sure that you learn how to be efficient with it as well. Make sure that you can use your firearm from either shoulder if you have to take an off-side corner. Make sure that you learn how to keep your distance from corners and do not extend your muzzle into an area that you have not cleared (you can give an attacker the ability to grasp your long gun). Ensure that you know how the long gun can be used at distance if you need to, and maker sure that you know your offset on your carbine or your pattern spread on your shotgun.
Massad Ayoob equates the handgun to the infantry role and the long gun to artillery. His meaning is that the long gun is better suited for stationary defense, while the handgun is well suited for mobile defense. Making the choice for a long gun in the house seems like it is a easy choice, but make sure you consider all variables to pick the tool that is right for your needs..