This is very un-hacker like. There has be better way to rank the comments considering you have so much information, specifically, graph of people with karma values upvoting/downvoting each other. Can't we just do simple variant of PageRank to rank comments? You can even simplify thing by having child comments inherit rank of parent (or may be adjusted rank). Individual users can set the noise level that they find acceptable in their profile. I strongly believe this is a ranking issue and shouldn't be left to humans with all of their potential to bias things.
Proposed system might work ok on head posts but there are lot of tail posts which have smaller audiences but interesting topics nonetheless. On those posts, minority opinions or "ridiculous ideas" would have lower probability of getting endorsed.
Add "Follow" feature and then you can see comment tree up the nodes that are created or upvoted by users who you are following OR the users who are N-edges away in the graph. You can set N in your profile.
Proposed system might work ok on head posts but there are lot of tail posts which have smaller audiences but interesting topics nonetheless. On those posts, minority opinions or "ridiculous ideas" would have lower probability of getting endorsed.