Phil's Rambling Rants
I have exactly the opposite worry. I figure that doing other people's songs is guaranteed to earn me unfortunate comparisions with better performers, so I write things, hoping that others will pick them up and see some merit in them.
(My little dream is that I'll be sitting in an audience one day when someone who hasn't a clue who I am decides to play a song I've written.)
My opinion, FWIW, is that song interpretation is a valuable musical skill that deserves recognition along with all the others. I've heard you at two cons -- I haven't been around long -- and enjoyed what you do. I'll bet that your music would also be appreciated during a one-shot...they aren't called songwriting contests, after all. :-)