Using Entourage Categories for GTD

In the PDF from DavidAllenCo. on setting up Entourage, I got the impression, categories are used exclusively for the @ lists. Is there anything wrong with continuing to use categories for anything else? As long as my @ lists appear together at top, does it matter that I categorize my contacts as usual?

Hi there

No reason to not use them in other places as well. We do recommend them for "Notes" too. Many people categorize contacts. Whatever you would find useful to maintain for yourself.

Cheers,