I will admit that I am a big fan of this show. With regards to the new sound system, I very much love it. I think that a great example of how much more it adds to the show would have to be how it is used for The Phantom's pre recorded part in "Notes." The sound is now done in such a way, that the voice goes back and forth between the speakers on the right and the speakers on the left, creating a more haunting effect then it was before. Before, it was just coming out of the speakers same old same old.
Also, with regards to the Christine understudy. Because Elizabeth is listed as an alternate, when she goes on, there isn't any understudy slip. Having been to the show and seeing both the main Christine go on (this was when Wills was with the show before her maternity leave) and seeing the alternate go on they never have an understudy slip.
"If you try to shag my husband while I am still alive, I will shove the art of motorcycle maintenance up your rancid little Cu**. That's a good dear"
Tom Stoppard's Rock N Roll