I would like to start by saying that legally I have no idea.
I think that less than lethal shotgun rounds would be a great idea for home defense. If someone is breaking into your house and hears a 12 ga being racked they will more than likely take off running with a brown stain in their pants. While you might not be happy with their entry into your house, wouldn't you rather knock them back with a less than lethal round (bean bag, rubber slug, rubber shot, etc.) instead of taking a life?
I also think that this is contingent on the neighborhood you live in. Correct me if I am wrong in saying this but in my opinion if you live in a quiet neighborhood, your intruders are less likely to be violent and are only there because they don't think you are home and are most likely unarmed. On the other hand, if you live in an area with a higher crime rate intruders have the potential to be more desperate and might be armed; if this is the case a lethal persuasion may be called for.
So in conclusion, I think that my decision on lethal vs nonlethal would be purely based on where I live and the potential threat I may encounter.