Interesting article! It's a shame the documentation is lacking :(

Oh, and as for the different sorting options:

• Hot sorts by the number of upvotes and how recent the post itself is
• Active sorts by number of upvotes and how many recent comments a post has (lively discussion ranks higher)
• Scaled sorts like Hot, but tries to prioritize or give more weight to smaller communities
• Controversial sorts by giving comments or posts a higher rank if they have an even mix of down votes and upvotes