Thanks, DR JoseSPiano. Perhaps I'm a geek, but I find this stuff fascinating.
Well, if you want to talk about being a geek... As I started playing off the "old" version of "Music and the Mirror" today, I would consult the new one to make sure that I incorporated parts of the new arrangement. And I also usually do vice versa too.
*And since I was fortunate enough to learn the show under the original pianist and musical supervisor, I also still consult that marked up - and in some cases, corrected(!) - copy of the score I used then from time to time.