As I watched the videos of just regular school groups performing, I noticed that the best performances were when the singers sang with SIMPLE LIVE accompaniment. In other words, the chorus sounded best when they were not overshadowed by SOPHISTICATED full orchestral accompaniment minus tracks. When the children were supported by just a few live instruments (piano, flute, bass, guitar, etc.), they tended to sing better IN TUNE and with more musicality and cohesion.
ROOM ACOUSTICS are such a determining factor for whether a performance will be successful. Let's be real. Neither a gym or cafetorium were designed for musical performances, yet they are the only venues available at most schools for performances. They have no carpeting or acoustic tiles on the walls to limit ECHO. They may have huge AC fans or Heating vents blowing very loudly -- of course during the performance! The only speakers may be of the "Dixie cup" order imbedded all over the ceiling. The Minus tracks will be broadcast through these little speakers, but the chorus won't. Balance may be impossible to achieve.
Too bad so many chorus teachers chose the more SOPHISTICATED minus tracks for their concert programs.