I am not a great fan of simply performing songs which are not well known in an attempt to "out-obscure" one another. A lot of the time songs have dropped into obscurity because they weren't all that good, and I'd rather hear a good song that I may have heard before than an obscure but very boring song performed by a smug person showing everyone how well they know the tradition.

On the other hand, if you've discovered an absolute cracker, bring it on! But I'll probably nick it. :)