Personally, I don't support total immersion. We adopted a child from China, as did several other couples. Our daughter was an infant, but two of the other families adopted older children. I know that for a time it was very hard for these youngsters not to be able to communicate with their new parents, and it is for their emotional comfort that I have concern. The children did learn to speak English and are both doing very well, many years later. But at the beginning, I can only say that the children seemed traumatized: crying and hysterics, or a failure to speak at all.
However, I have also taught English in public school. Whereas I might get a non-English speaking student for a short period of time in class, usually he (she) would be moved to a lower-leveled class, and given time in his schedule for instruction in his native language and with his new language.
While these youngsters will learn, as the brain is still able at younger ages to adapt quickly, my concern is for the child who is totally immersed in a new culture and language: there seems to be a sink or swim attitude here. Traveling to another country that does not speak my language can be frustrating for me: case in point, the ham and pineapple pizza we ordered, and the tuna and onion pizza we received. This is humorous enough now, but at the time it was frustrating. Focus now on a child that has been removed from all he knows, all he is comfortable with, engaged in learning a new language, surrounded by an abundance of kids he does not understand. If there is any taunting of other students involved (and kids can be cruel), the child is isolated and unable to share his concerns until he goes home.
The learning of a language may be achieved with great success by total immersion, but I believe that the needs of the "whole" child need to be addressed. I'd vote for the bilingual classroom.