I have 2 Master's degrees, one earned through a major nationally-ranked research University, and the other through Western Governor's University, which is an online CBE program. My coursework through WGU was equally rigorous, but the format let me concentrate my time where I needed to learn and zip through what I already knew. I felt like I actually learned a lot more in my WGU program than in the traditional one, and I finished in less time (because it was at my own pace and my pace was pretty fast) and at a much lower cost.

I would love to see my kids in a well-designed CBE program. It would be in many ways a more grown-up, structured, idealized version of what I expect from a really good Montessori. Montessoris often bill themselves with "your child can go at her own pace" but that only really sort of happens.