Perlmonks is the best example I've ever seen of maintaining a great place for smart people. It's been running non-stop for a decade. It's very open (even allowing anonymous posts) but has community rules that mostly reflect common decency. Over the years I've seen countless disrespectful newbies and trolls turned into contributing members of the community. The solution there has been to have long-time members volunteer to enforce the published rules in a consistent and fine-grained way. It requires implementing a user hierarchy, but we already have that here with the "editors". Publishing some rules and systematizing the editor controls would solve most of the problems reddit has faced.