I went with the definition of "less lethal" ("...means of self-defense that have much lower risks of death to others"). I understand that these methods are not entirely un-lethal. As for these methods being significantly less likely to stop attacks - I haven't found any stats on that. Did you have a specific report you were citing? I'd like to see it. As I said, it's just something to consider in the self-defense justification, and something I'd need to see more empirical data to analyze fully.

Also, Castle law requires that you be defending an inhabited residence (or car, office, etc.). The basic rationale is that someone breaking and entering poses an unknown, but quite high, risk of violence, and so deadly force is authorized to protect those within from that violence. The flip side of this is that non-home structures (detached barns, unused houses, etc.) are not eligible for lethal-force-using protection. That's why I said that you're not allowed to use lethal force for defense of property alone. It requires that the property be inhabited.