Quite honestly, I wouldn't worry.
If you compare ourselves to other betas, I would think that we are doing fairly well.
We have an incredible user base
We're friendly and all, and we've got experience. We know what we're talking about, and we're willing to help others. Also, an "avid" user is basically just anyone with over 200 rep. :)
We've got voting
Many sites are falling victim to the "no voting" issue, such as eOS, and Law. As a result, the full community can't moderate effectively, they receive large amount of questions from new users, but only a handful can really look to them, and vote... We've got those users, and a lot of them.
We're slow, but we're ever going. I think we're going fairly well.
How do we improve?
Migration paths aren't even available anyway for beta sites, and all migrations have to be done through a moderator, anyway. It won't really help.
Instead, share it with your friends. We're trying to see if we can regain contact with the OSI now that we've got an established leadership here, and we're just waiting for the response on that.
About the stats, I've looked at the stats that are available to myself, and I've noticed a sort of trend. There seems to be a correlations between the number of questions asked, and the number of visits that the site receives (like a result of hot network questions). It seems to have been good for us, we get more users, and more visibility as that happens. We get roughly 150 visits a day, of which about a third are newcomers to the site.