Good points, Paul. If a song is a sing-along standard like Run Sinner Man or Puff the Magic Dragon, I will pretty much leave it alone. But overall I am a performer, not a preservationist. I change tunes and lyrics all the time, sometimes to fit my musical or literary voice, sometimes to elicit a particular response from my audience, sometimes just to discover what happens. Even when I intend to replicate a song as I heard it or read it, it doesn't always come out the same way. That's because, as I wrote at the beginning of this thread, I recreate a song each time I sing it.