This is my school of thought; it would be nice to know which are the hot comments. Previously you could skim through only the higher rated ones if you were in a hurry, but now you sort of have to trawl through masses of text to find the gems.

One idea i thought might help the whole points vs. no points situation is changing karma from being the total points over all posts to just being the average points over all posts, so then people will be motivated to create fewer high-quality posts to boost their karma, rather than just trying to saturate HN with lots of posts that nab a point or two each. (somewhat hypocritical maybe)

Yeah, I like Hacker News without numerical indications of karma, but some sort of idea of how popular a comment is could be nice.

Doesn't the ordering of the comments on the page fulfill that requirement?

Ehh, sometimes, but I've noticed that sometimes the system orders new comments with not a lot of karma near the top.

I am pretty sure that's based on the user's average karma.

With just this, it would be fairly easy to learn how many votes translate to what color, and you're back at square one. Maybe color as some function of upvotes on the comment and proportion of all upvotes (maybe only those comments at the same level in that thread)?

Particularly if it was relative to other posts in the thread, and maybe only after a certain threshold, so it doesn't serve as disincentive to posters who are just late to the party, but still allows users to quickly see the best posts.