Reddit says: “The reason we didn’t display more than 100 comments in the past and
still don’t display more than 100 now is because of bandwidth and
rendering time (both ours and yours).”

I think that’s a mistake. First: bandwidth of a zipped list of a few 100 comments is VERY small: a few K only. Smaller than 1 image often. Second, displaying a long page with comments is fast: here’s an example (380+ comments). I am thinking about the same issue (you have to cap it somewhere, no point in displaying 1000 comments on 1 page?), but as long as there are no threads that hit 1000 comments, I think I won’t bother. I don’t think the reddit solution of only showing “good” comments is right. It breaks the conversation flow.