Interesting! I use Evernote too but only for longer notes at the moment.

My Workflowy GTD approach has actually changed a bit since I wrote this article — I now use lists for projects, and tags for priority, context, people, and other things.

You can add as many tags as you like so you can easily search and even bookmark specific pages (e.g. this page shows everything tagged #next, which includes my next items across all projects).

I think this is more flexible and has many of the benefits of the system you describe, though as far as I’m aware all tags have to start with a #.

Let me know if that’s useful! I might do a rewrite of this article some time…