The character limit of ID3V2 tags is huge compared to V1. I blow the buffer on most of my mp3s in V1, but not a single one in V2. Give it a shot.

Why are you uploading the same file several times? What I mean is, why don't you have a separate directory for uploaded mp3s and one for mp3s that haven't been uploaded to the RIO. That is a simple way of keeping it sync'ed with your collection, unless I totally misunderstand what you are trying to do.