Two of my children spent their junior years away from their boarding schools to attend SYA France. It was a transformative experience for both (different years), and they characterize their experiences as an absolute highlight of their lives. One became fluent in French with a native-speaker accent; the other became nearly fluent but retained an American accent. One went to Harvard and the other to Stanford, so it can’t have hurt their college admissions too much! My other two children were unable to attend SYA because of athletic commitments. One took a gap year in South Africa and the other attended a different fall-term program his junior (high school) year in Italy. Those experiences were fine and rewarding, but not nearly as immersive and life-changing as SYA.
I had some of the same concerns expressed by parents in this thread about missing out. My daughter said, “Mom, this is how I want to spend my junior year. Just because its not the same as YOUR idea of my high school career, doesn’t mean its not right for me.” In my experience, it does seem that the kids who would feel like they were missing out on important parts of the boarding school experience, would never consider a year away. Those who are interested are likely those who would benefit enormously.