Hello AJ,
I'm not using tags at the moment. However, they're more flexible than contexts, so you could use them for one off notes, for hash-tags or for storing information like the cost or the time you've spent on a task. If you have an efficient system already, then don't worry about it and don't bother using it. If you come up with a new way in which you want to categorise your tasks for filtering, then you'll have a spare parameter which might be useful.
Stéphane