WV_Gunner, you are right on.
A good Home defense weapon has 2 requirements. You have to have access to it, and you have to be comfortable using it. You can't use a weapon you don't have, and you will be less willing to use a weapon you aren't comfortable with.
If you only have the option of having a single shotgun for home defense, first figure out who all in the household will be capable(either by decision or by physical ability) of defending the home. If you live alone, it's only you. If you are married with children, you need to consider who is going to defend them if you aren't home with them. Select a weapon that all household defenders can comfortably operate.
A single round of .410 00 buckshot has the same penetration as a similar round of 12ga buckshot. The only difference is that a 12ga typically has twice the number of projectiles per round, which means more wound channels and more stopping power per round. This doesn't mean that the .410 isn't an effective round, it just means that 12ga is a more effective round. However, that doesn't matter much if you aren't comfortable with it. Almost any adult can physically withstand firing a single round from a 12ga, but many are uncomfortable doing so because... it kicks like an angry mule.
If you aren't an experienced shotgunner, Go to a local gun range and rent a 12 gauge shotgun. Practice with it for 30 min. If you don't feel comfortable with it, or you don't expect that you will take the time to train to be comfortable with it.... DON'T BUY ONE. If there are other home defenders in your household who aren't comfortable with it, and you can't get another weapon for them also.... DON'T BUY ONE. Almost anyone can be trained within 30 min to be comfortable with a .410 shotgun. If that's all that you and your home defenders are comfortable with, it's better than a 12 gauge, because you all are actually comfortable with using it.
A reliable multishot shotgun is a better defense weapon than a single shot. The more rounds it will hold before you have to reload the more versatile and effective it is.... So long as it is reliable. A semi automatic shotgun with 15 rounds is FAR more effective but ONLY if it is reliable(many are not). If a firearm jams and you can't quickly clear it, you are left with a club(and not a good one).
I personally rely on a .410 saiga with a 15rd magazine. All of my household defenders can accurately fire 3 rounds on target faster than most can fire and rechamber their 12gauge pump. Most importantly, we are all comfortable with it. I average less than 1 jam or failure to feed every 500 rounds, which makes it pretty darn reliable. Most stock saiga shotguns aren't near this reliable.
Don't worry about what everyone else is using. Go to the range and find what YOU and your home defenders are comfortable with using. Then, find something reliable in your price range.