billt,
Those are some very good observations. Regardless of what weapon system you decide to use, you must consider the environment you expect to operate within.
With respect to the suggestion of using Trap loads for home defense, I would respectfully reconsider your selection. While just about any shotgun round at contact distances will do tremendous damage, most shot loads lose their energy very rapidly. Additionally, the shot does not have the mass needed for reliable, adequate penetration of at least 12". Consider this, if you select a shotgun load that won't penetrate sheetrock, it's not going to penetrate 12" of human body either.
If you select a shotgun as your primary defense weapon and you have concerns about over-penetration, I would recommend using a #4 Buckshot load. #4 will still provide the necessary penetration needed to incapcitate an aggressor, but it will not penetrate as much as 00 Buck.
USSA-1