imho, The value of a community is in its members, not in the software. Sure, UI can have an effect on the ability to build a community, but only upon the edge cases.

What made HN successful isn't the presentation, but the character of its members and its association with Ycombinator.

Whether wallstbeat succeeds is more a function of its ability to attract valuable commentary and users willing to share analysis in a public forum. Failing this, it's vulnerable to the same pump-n-dump trash you see on Yahoo! finance and other sites.