I think our headcanon is similar. I tend to think that if she just got away from Diamond Tiara she would be a decent filly. Probably still have problems understanding middle-class fillies like the CMC, but would be willing to be friends nonetheless.
They wouldn't step out of their roles, for sure... but it would be nice to evolve them a bit more. To show more than one aspect of their personality. Most ponies have a distinct and varied personality - I'd like to think we just haven't seen their "other sides".