Another thought if you're still thinking about this and monitoring this discussion - give people a limited number of "show stopper" flags intended to draw the attention of moderators. They only get say 1 or 2 over the course of a month - much like dating sites to indicate importance (e.g. plentyoffish with their 2 roses).

These could be used either to reward or punish depending on how they're designed but people would use them sparingly if they're given after a certain criteria is reached (e.g. age of account, karma points, etc.). The purpose would be to cut down the noise that moderators/you have to deal with. Thus there could even be karma points and a red flag/green flag score.

The red flags might only be visible when you click in to their profile for example so as not to draw attention to their presumably highly offensive postings while the green flags are visible highlighting extraordinary comments.

PS I hope you figure out a solution to this as I'm sure I'm not the only one who was alarmed by your comment "I occasionally find myself thinking lately that I just don't want to be here anymore."