I don't think GoKunming should overreact to the recent hubbub. I think that the forums have been running reasonably well since the changes of a few years ago -- most people have been taking the hint from downvotes.
The recent problems boil down to one particularly nasty troll who was oblivious to downvoting and other negative feedback. It seems clear that moderators should respond more quickly and assertively if such a case arises again in the future. At the same time, to paraphrase @ASatiricalBloke, some light trolling can be useful in keeping the conversation bubbling along, so it would probably be counterproductive to let Miyamoto's unique toxicity lead to overly-aggressive moderation.
If I might, I would propose a couple of heuristic tests for the moderators:
1. Would this thread be easy fodder for a local media story about how terrible the laowai are and/or awful things they say about the good people of China?
2. If an expat refers a Chinese acquaintance or student(s) to the GoKunming website, would seeing this thread later the same day cause them to regret doing so?
I don't recall any threads in recent years apart from Miyamoto's that would meet either of these standards, so I think the adjustment in moderation should be fairly circumscribed.
Regarding feedback about the site more generally:
The news articles are always welcome, so I have been a bit disappointed by their scarcity of late. Regarding content, the one about pollution and brain function was the only one in memory that made me scratch my head -- it seemed like it could be relevant to almost any city.
The News Wire section is also helpful in terms of finding Yunnan-related articles that I would never come across on my own. You might want to feature that more prominently, since it's sort of hidden away at the bottom of the home page such that I often forget it's there.
Finally, finding quality resources for services such as plumbers and electricians is generally not easy here, so it would be great if there were a section with listings and reviews -- sort of like an Angie's List (angieslist.com) for Kunming. [Edit: Or maybe just add a relevant category / categories in the 'Listings' section.]
Having said all that, I generally like the site and appreciate the role it plays. Keep up the good work.