We could avoid all that and just have a way of correcting comments (with history, diff, and all that) which would show up upon clicking, say, "show edited version" or whatever. By default it would display the original version, but if someone wishes, one could display the edited version. This way the noise would be hidden. Perhaps to be able to add such corrections to comments, you would have to have at least n_1 karma, be registered for n_2 months, and so forth as a defense mechanism against trolls.

I am sleep deprived. I hope my idea comes across properly. It sounds good to me right now, might not sound good tomorrow. :P It is definitely complicated though and not sure it is worth the effort to implement and maintain.