Generally, subdomains don't recieve as much "popularity" as domains. Unless you have that topic covered with a bunch of keywords in it and your domain/subdomain practically that keyword then you might be on one of the front pages but otherwise; probably not. Meta tags don't help much because certain search engines don't look at the meta tags because some people may spam them. I don't think google searches using Meta tags, but instead keywords in the content.
I do know this - xenforo dropped the ball by not keeping the vbulletin reputation comments as a feature. The loss of the Reputation comments data when we switched to Xenforo really was the death knell for the site when it came to all the users that left. I know I missed it so much and I got way less interested in the site when that feature was gone and I run the site.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory