Student Exchange Programs

I’m thinking about doing student exchange next year. I’m currently looking at a semester in America. I’m in my last year of high school, so if I go next January, I’ll miss the first couple of months of year 11 (first year of college)… would that be doable?
I’m leaning towards EF ( http://www.ef-australia.com.au/highschool/ ) STS is a second option ( http://www.sts-education.com.au/australia/hs/home/ )
Has anyone been on student exchange with these programs, or can recommend a good exchange program?
Thanks