For what it's worth, I've got my own Disqus alternative: https://github.com/alexandru/TheBuzzEngine

You can see it in action here: http://thebuzzengine.appspot.com/

However, on my blog I have switched back to Disqus. Mostly because the only thing bothering me about Disqus is its bloatness which makes the page take a performance hit, but other than that it works great and you can export your comments at any time.