I've been following these MM threads for 2, 3 weeks. Love them. Keep it up.
Going to weigh in with some stray observations, since I haven't watched (or listened to) JCS in years. I think it gets tagged with the "rock opera" tag because of the similar themed but more traditional musical/folky show GODSPELL. JCS is kind of the start of the "British invasion" of Webber/Rice/Mackintosh musicals that peaked with Opera (for ALW) and Miss Saigon (for Mackintosh) where it became spectacle over quality. From a musical nerd historical perspective, starting in the late 60s/early 70s Broadway wasn't making a whole lot of money and that's when you started seeing the more stripped down shows (ala The Fantasticks, Godspell, etc). ALW and Mackintosh kind of flipped that on it's head with their shows that are more about the SHOW! then about the music. You ask people what they remember about Opera, Les Miz or Saigon and you get "the chandelier" or "the barricade" or "Javert's suicide" or "the helicopter". You are seeing the genesis of that with JCS, which is why it probably works better as a stage show then it does as a movie. The movie, imo, tries to hard to skirt that line between old Hollywood Biblical epic and new Broadway spectacle.