Excellent choice! I would have liked to have used that approach, but it doesn't jive with my wife's personality.
Aquinasfan,
I don't know if it's too late for your kids, but there are many different kinds of Montessori schools. In some schools, the only part of Montessori they use is the name. My kids were in a Montessori preschool program which was nearly perfect for them at that age. They got to choose what they wanted to do and there were plenty of fun choices. I especially liked the math tools, and I'm a tough customer there because I have a degree in math. My only complaint was that the teacher seemed to think that my kid who was reading at a 4th grade level should work in a reading workbook that was trying to teach her the alphabet. We had a little friction when I (nicely) tried to explain that it was stupid for a kid reading the Narnia stories to have to circle "R" when she sees a picture of a ring.
Anyway, my point is that no school is perfect, but if you have more than one choice in your area, it's worth looking into another school. Second piece of advice is that a school can be great for your kid for some number of years, but schools, teachers and kids all change and you should re-evaluate your choices every year. Best of luck to you.