At our middle school, the band and orchestra directors make a point of acknowledging kids who get into all-county and other honor bands that they have to do paperwork for. They just put in a brief mention in the online newsletter. The kids also get acknowledged at the end of year school awards ceremony. No acknoweldgement for anything outside of the school even if it is more prestigious.
I have a kid who is extremely proficient at her instrument and loves to perform. She would rather die than perform in front of a bunch of her middle school peers at some kind of assembly that they have been forced to attend. She understands that most kids at her school outside of the band/orchestra program have no interest in hearing that type of music. I'd be cautious about encouraging a performance before the school. I could see it backfiring if the kids are not respectful/paying attention.
