While a substantial carry gun is certainly capable of home defense, I am of the belief that most people are served well by having a dedicated home defense pistol that is not a carry gun, but stays in a quick-access safe ready for the specific role of home defense. The most likely location for this particular gun is the bedroom where you sleep. As an advocate of home carry, actually wearing your carry gun while even at home gives you the only true immediate access to the firearm. While sleeping, though, you obviously won’t be wearing a gun, so a dedicated house gun within reach makes sense.
One of the benefits of a dedicated house pistol is the fact that concealment is really not an issue, so a full size service pistol is not a problem and is most likely ideal for this role. One consideration I urge, however, is to go with a house gun that is as similar as possible to your carry gun so that you are working with familiar hardware. This is where working within the offerings of a single handgun family comes in useful. For example, if you use a Smith and Wesson M&P Compact as a carry gun, or even a Smith and Wesson M&P Shield, then why not set up a full size M&P pistol as a dedicated house gun? If your preferred carry gun does not have a bigger family member, then at least chose something with as similar a manual of arms as possible.
As an example of this I utilize a Glock 19 as my dedicated house pistol. Obviously, it is identical to my carry gun, the Glock 26, in all but size. The Glock 17 would also make good sense here, though I find the additional size of the 17 really does nothing practical for me over the 19, so I just use the Glock 19 as my house gun. Besides the larger size of the 19 compared to the 26, which provides at least a slight advantage in shooting performance, the 19 is for all intents and purposes a full size gun, and it has a light rail on it. This is a feature that I strongly suggest in a dedicated house gun.
I simply don’t find a compelling need for a civilian to conceal carry a gun with a light on it, though carrying a hand held light is essential. However, for a house gun, a weapon mounted light makes perfect sense. When things go bump at O-dark-thirty and you get out of bed wearing only your boxers, having everything you need on the gun is a huge advantage. I highly suggest putting a weapon mounted light on your house pistol, and getting training it the use of a weapon light is a must. Along with the weapon light should also go a hand held light that lives next to your house gun.
If you live in a democrat controlled communist state you are probably limited to 10 round magazines, so using extended magazines is moot. However, if you live in a free state, the use of magazines that extend beyond the grip of even a full size gun provides a capacity advantage with no down sides since the gun is not worn concealed on the person. Having a gun with a magazine holding 17, 18, or more, rounds in it gives you more on-board capability. This is a good thing since, again, the gun might be all you have time to grab and you are probably not carrying a reload in your boxer shorts.
In closing, I will again suggest that, if you are a serious practitioner of personal protection, the selection of three handguns are most likely in order: a primary carry pistol, a deep concealment pistol, and a dedicated house pistol, will serve you well. I hope this series on this three-gun setup assists you in making your own choices.