Of the understudys I have seen, Daniel Coll impresses me the most. The show could do far worse if Tim leaves than put it in Daniels capable hands. He also has chameleon like qualities on stage portraying the different parts during the show. Gillian has a great voice, is a good actor but for me doesn't quite "fill" the stage like Haydn does. I don't think it is that she isn't very good at the part, she is but Haydn is quite simply amazing.
I also agree with the comment about Alex, it doesn't quite work. The matinee show the day James left. George was playing Billy and both Gillian and Alex were understudying. "Born to Boogie" just didn't seem to work that day.
As for people leaving, it will be a real shame if Steve Elias leaves as filling his shoes will not be an easy task either.
All great things must come to pass. We know the first will soon be last and in the ground we may be lain , but a seed is sown to rise again.