I was just living in Alamos (southern Sonora) for a month. It's a very beatiful country. I would encourage you to take such an opportuntiy as english can be a very helpful language for the locals, and learning spanish in a homestay is a great way to do so! Also, even though life can be less comfortable, the hospitality in a Mexican family is amazing (at least where I stayed). It's an honor to them that you would choose to live in their house.
PM me if you have any other questions, although I must admit that I'm not familiar with the region your interested in or the program your looking at.
BMW