I have ~1900 karma so I'll be one of the endorsers ... but I am not sure I want to be. I think this is a very aggressive change and one that puts too much power in the hands of people like me. Just because I have enough free time to sit around and rack up HN Karma doesn't mean I should control the speech of other, newer users.

Also I think the delay caused by waiting for endorsements on comments will really kill a lot of fast-moving comment threads. it will make it harder for people to have a discussion until the 1000+ karma gods take notice of the thread and throw enough endorsements around to make the comments visible.