I have always heard that the "vine of the soul" was always specifically referencing the B. caapi vine, and that ayahuasca was specifically a B. caapi preparation. I've been told it's almost offensive to call a mimosa preparation (also a common amazonian plant) ayahuasca. I had never heard anyone refer to Acacia nilotica as ayahuasca before. I am not one for traditions or spiritual trappings, so calling it that doesn't bother me. I just wish I had met Anubis on my ayahuasca trips :P Interesting post!