The design change you mention did not happen in its tryout in New Jersey and it really helped the Broadway production. I agree that their rise to popularity was too quick but it didn't bother me a lot. I wasn't a fan of the downbeat ending at Paper Mill because you left deflated.
I also did not like the Broadway ending where they still achieved fame through touring. It seemed extremely unrealistic, and stuck out in an otherwise well-crafted show. I don't think they had to be downbeat at the end, but I think it would have been more realistic for the band to have a quiet, local life where they were content.
