Rock on with your bad self! If you can differentiate with some kind of value not currently available or poorly implemented elsewhere you've got a shot.
Supertopo's the home of crusty legends, dirtbags, and the ocassional crusty legend who is also a dirtbag and a luddite. While the forums there frequently serve as THE source for up to the second info on what the hardman crowd is up to the signal to noise ratio is fucking abysmal. Clean that up and you've got something.
rc.com and mountainproject are basically identical in their strengths lie with an active younger community and good route databases. rc.com tries to be too many things to too many people though so the implementation is muddled, whereas mountain project looks like crap and gets maybe half the traffic but the route content is typically much better that rc's. Clean up RC's mess, harness their community and somehow figure out a way to get the same kind of quality content as mountain project, and again, you've got a shot.
8a is spraylord paradise and home of anyone who's ever dreamed of scoring that big chalk sponsorship. I'd leave well enough alone here.
Edit - BTW, given the domain name, you wouldn't happen to be hanging out with offwidth climbers would you?
To be honest, I'm a relative newcomer to the climbing world. I've been at it for a year, and still haven't found a news site or forum that is as addictive as HN.
Re offwidth climbers -- Nope, not really. Do they have a reputation for thrutching?
"thrutching" may be the only term in the english language that sufficiently encapsulates the act of offwidth climbing, even when you're doing it correctly.
Also it would be nice if there was room for opinions even when creating topics. I know your community page[1] says submissions should be factual and neutral. There are all sorts of things I wouldn't post based on that. For instance my favorite summer alpine climbs in the Rockies... Since it would be neither factual or neutral.
I wrote that when I was working on the "every topic is a wiki page" feature. I was in the mindset of how wikipedia operates, but I see your point that it would exclude a lot of interesting posts. Removing it for now :)
edit: climbing comes up on HN every few months, we should start a mail list or figure out where everyone is and plan a trip or acquire gym partners.