you should also track the comments moving from thread to thread (when an admin moves comments from one thread to anoter), comment shadow banning, post popularity based on upvote counts (lots of times, post get to the front page with only a few votes), or maybe even track how fast posts get deranked

I'm using it to track common items here and on Lobste.rs (and Proggit):

http://gerikson.com/hnlo/

Here's the endpoint for the latest 500 submissions:

https://hacker-news.firebaseio.com/v0/newstories.json

here's the one for the current top stories:

https://hacker-news.firebaseio.com/v0/topstories.json

It's actually quite nice to work with. I don't know how to keep track of comments moving from thread to thread, because that's not a metric I'm interested in, but it should be possible to track somehow.