Did any of them actually use 100% cocoa butter? What I read from nietzchilitis, it seems that she used "Palmer's: Cocoa Butter Moisturizing Lip Balm" containing cocoa butter, but the other ingredients might not be so "natural" as she said (at least the paraffinum would be one ingredient which would make me not want to use it):
The problem with using 100% cocoa butter probably is that it's stiff/hard at room temperatur and only melts at around 34 degrees (Celsius) or so (similar to the shea butter that I have), so it would be hard to apply it to the lips.