The answer to the problem with categories is in the response to a comment I posted on opml.org under the aforementioned posting. Categories on OPML/WordPress looks pretty good. Right click or Ctrl-Click on Mac to get the category popup. Pretty slick.
I find it funny that I prefer OPML over Ecto, OPML is not as flashy, but I like the feel of the product. I’ve been using the editor for taking lecture notes this past semester. I’ve tried trial versions of Circus Ponies Notebook, OmniOutliner, and Notetaker. I keep coming back to OPML.