as long as the meta data (tags) are correct and updated with comments and your media player supports both instant search and smart playlists (i have to admit itunes is the best at this) i see no need of sorting your audio in a complicated structure
add to that itunes can manage several libraries which can as far as i understand can seperate your gigs audio and your personal audio (personally for that purpose i just use a different player) hope it helps you
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