I am kind of skeptical of killfiles, TBH. The idea is good in theory, but I've seen forums where the existence of killfiles basically removes all incentive for self-modding - making the trolls and idiots invisible is a lot less trouble than making them *stop* being trolls and idiots.

And the result is that when new people come to the community, all they see is the trolls roaming unchecked, and they get turned off. It *might* work better on LJ, because people moderate their own spaces instead of depending on weight of numbers, but I would want to specify that option #2 only works on journals and communities you don't control (though possibly with an option to also ban_set in your own spaces.)