That distinction is important to understand. The dynamics are not the same. So what would your major challenge be? Is it the quality of the teachers in the French immersion or French as a second language programs?
We have often heard that some students have gone through the entire program and spoken no more French at the end.
You talked about the need to have direct contacts, as with the student exchange programs operated by the Society for Educational Visits and Exchanges in Canada, or SEVEC, but do you have reasonably good-quality teachers?