I had originally started the project to grab Flesch-Kincaid grade levels, but it was taking me 45 minutes to analyze about 20 pages of comments, so I switched it out for Automated Readability Index.
I really wanted to include HN, as I feel it's in a period of social shift, but it wouldn't have the same sort of statistical significance due to its size (it would most likely just be meaningless jarring jagged lines across the graphs). If someone can think of a good way to include HN, I'm all ears. I'd also be interested in other methods of writing analysis that I could include.