Peg
You mention John Renbourne in your post. Funny for I had heard that he did have a somewhat unreliable reputation and did not turn up for a show that I attended but I have not heard the same about Dick Gaughan.
As for the string-breaking. I think he must be the fastest string changer in the west (or the east). I am sure you will have a wonderful night. Will you let us know what your thoughts are after the show?