"Webber's "POTO" beat it to Broadway, as it was already established in London due to the fact that the novel is public domain there. Yeston had trouble securing the rights in America"
How can that be true? Under U.S. Copyright Law at the time, works entered the public domain 50 years after the author's death (it has since been extended). If Leroux died in 1927, then the work would have entered the public domain in 1977. Did I miss something? I think the problem with "securing the rights" was more about the fact that Cameron Mackintosh and the Really Useful Group put some restrictions on where the Yeston/Kopit show could play in proximity to the ALW show (also explains that sad tagline Maile quoted above--all about avoiding legal trouble). Certainly not the kindest move by Cam Mack and RUG, though kindness is not exactly what they're known for.
That said, I have not been impressed with what I've seen and heard of the Y/K version and I think the ALW score (and even the somewhat mediocre book) serve the story much, much better. People forget that the original novel is not one of the great masterpieces of French literature--it's just a very good mystery/romance--so it's not a tragedy that ALW's version doesn't do much with most of the characters. I'd rather see an adaptation like ALW's, where the characters aren't fully drawn out and the book stays more or less true to the original, than an adaptation that creates fuller characters at the cost of groan-inducing deviations from Leroux. Granted, I suppose I'd have to see a full-scale production of the Y/K version to truly judge, but as someone who has both seen the ALW version and read the novel numerous times, I can safely say that ALW (and Charles Hart, and Hal Prince, and Maria Bjornson) captures the novel's soaring gothic melodrama perfectly.
"If there is going to be a restoration fee, there should also be a Renaissance fee, a Middle Ages fee and a Dark Ages fee. Someone must have men in the back room making up names, euphemisms for profit."
(Emanuel Azenberg)