Just like to say I thought the article was great. I also picked up that the view was not necessarily the best place to filter the categories and also that the category.id was probably a better attribute to search on.
However, like you said the article was not about best practices. It gave me the chance to think on my own and see if I had learn't enough to write some of my own code. To my complete (albeit undeserved) surprise, I had picked up enough from your two tutorials (and a quick glance at the API docs) to make the changes I felt necessary.