Some honest feedback: I personally wouldn't switch to this from HN. The reason being that the main problems you're trying to solve (encouraging constructive discussions, influence farming, etc.) are simply not things that have been an issue for me on HN. If anything, I come to HN specifically because the majority of discussions are pretty constructive, and the karma points are hidden so no one really cares about (or can tell) a user's influence.
The rest of the benefits like markdown support are cool, but it's also kind of nice that the focus on HN is on the content versus formatting.
My two cents. Congrats on shipping!