This won't be a popular opinion....but I saw Jamie in Moulin Rouge recently and thought he was good, but definitely not great. He had zero chemistry with Satine, some of the set pieces totally overwhelm any kind of performance and his acting was fine at best. Part of that is the fault of the show, I think, rather than him. Moulin Rouge is a glorious, wonderful film but I (personally) don't think it works all that well as a musical. It also has that incredibly irritating habit of attracting audiences who are desperate to sing along
However, I can absolutely understand something like Once really working for Jamie. More emotional, more understated, less faff. I actually would have liked to see the show tbh, but fuck that at those prices plus travel. I've also seen Carrie in Les Mis....and she sounded pretty bloody good. I knew bugger all about her at the time - but she was genuinely great in the performance I saw. Shame about Carrie the person....