No way to really know I suppose. I'm no massive Hugh Jackson fan either. He sold out the O2 arena in London for 6 nights doing this sort of thing so you'd imagine they have a fair idea of what they're at.
Who knows, could be a disaster but then it might not be. Not a bad thing to try something different every now and again and mix it up. It's certainly a way to get people talking about the festival though and promote the other nights at the same time. I enjoyed the Greatest Showman and am currently in the same boat of the other half looking to attend this.
Ah well an experience if nothing else