I think it comes down ultimately to what will stop a threat...However, I think if you go for the exotics, (bolo, chain, flechette, etc) you open yourself up for trouble - beyond over-penetration. And old retired LEO told me he always stacked his rounds - OO and slugs and I followed his advice for years, but am rethinking it - thanks in large part to suggestions on this very board...I am however comfortable using 00 in my home defense role and will continue to do so...Birdshot to me is for birds and not putting down a threat at 2:20 in the morning....