Золото Акапулько, I think it's a real benefit for a teenager. I tried to participate in such a program (in Voronezh there was (and, probably, still is) a special company "Open Planet" which used to work in the sphere. I was invited to the American embassy , but they didn't permit me to enter US (without any reason...)
If I could do this for my daughter, I would certainly do it: first af all, it's useful because of the language practice. And secondly, I would be glad if I could at least in any way "neutralize" this terrible age, I mean reduce potential harm which this age may cause (do you understand what I mean?) The less time she'll spend "in the street" being 15-years-old, the less things I'll be afraid of... (May be I'm too apprehensive (afraid of) but I know that US, for example, are much more "safe", "problem-free" than Russia... To my regret...
Are you planning to get rid of your children?
Ah, my class-mate participated in such exchange. I don't know whether it is connected or not, but he turned out to be much more "creative" and brave.