Yes completely agree about PepperThere's only 7 important casting decisions to make, and Sophie and Sky definitely aren't any of them. There's been some IMO dodgy castings in the past, I saw a really dodgy Sophie who just didn't work for me.
The Dynamos, the Dads and honestly, personally, Pepper are the key casting choices.
Pepper is important because you need the right Pepper for Does Your Mother Know, or it falls flat. A great Pepper elevates that song.