This was a really great post. I wrote one a while ago about how to craft a good comment. Yours was much more in-depth here, but what I like is that you talked about engagement. One of the points I had made before was try to ask a question in your comment. It will start a conversation and build that relationship/connection. It also shows that you read the post. Thanks for writing this up, I am going to reference it when people ask how to comment well.