As a long time lurker and reader of HN I really hope that you reconsider this change. I made an account just to explain why I dread the impact of this change on the quality, openness, and character of discourse at HN.
Put bluntly this change inspires a visceral feeling of loss and disappointment in me. I have viewed HN as a community where anyone can participate fully if they have something useful to say. This change feels like it will destroy this character of HN and turn it into a system where elites will have all the knowledge of a discussion and the rest of us will not. They will be able to incorporate ideas into their own posts before others can and can choose which ideas get general airtime. Particularly in low traffic stories this feels unjust and noninclusive.
I really enjoy reading the comment threads at HN and some of the best comments come as replies to comments that are unlikely to get endorsed in this system. This is because this system contains powerful disincentives for approving anything other than comments that will universally be viewed as high quality. If you approve enough comments that are viewed as low quality by moderators you will lose your ability to even view non approved comments and therefore your ability as an elite to fully participate in discourse at HN.
When this goes live hopefully people will be very very liberal with approving comments and people will do the public service of approving most comments in a pending global queue quickly. For me it will be very sad that I cannot read the lone, often very informative, comment to a story that will never make it to the front page but that nonetheless I and other lurkers want to see any response at all to the story. I am willing to read the trolls if I am allowed to read those who will be neglected by +1000 karma users.