Just my two cents in terms of Montessori:
I don't yet have children, but both my sister and I attended Montessori school when we were kids. Yes we were blessed with parents that nurtured our intellectual growth at home, but I remain convinced that even with that, we would not have adored learning as much had we been in a rigid standard environment that is found in most schools. We attended Montessori from Kindergarten until the end of 6th grade, and when we went into another school in 7th, we both ended up in Honors (advanced) classes for every subject that gave that possibility (math, english, and science). We were also a year ahead in foreign languages, most likely because we started spanish classes in 3rd grade in the Montessori school.
Yes, it's very possible for the free-learning method NOT to work for some children, and if that is the case, I'm sure you'll be able to tell after a few months that Montessori isn't for them. However, if it is, and the child learns well and happily, I strongly believe that it's worth it. I doubt I would have had the grades I did in High School, or graduated the University I did, had I not been to Montessori as a 6 year old.