It would be extremely useful. I completely understand what you mean about the need for accountability; when my kids were first in the charter Montessori in FL, it was so hard to figure out precisely where they were holding and what they were learning in relation to where they would have been had they continued in conventional schools.
I have more to say about the public/Montessori hybrid and the compromises it requires but maybe others aren't so interested and we should talk about it via email? Suffice it to say that you definitely relinquish some independence and the ability to go pure with the Montessori method, and that loss is not trivial, even if it is necessary; without the public charter aspect, the consequence is that Montessori education is available only to a privileged few. (Ironically, exactly the opposite of how Maria Montessori started, as she was working with otherwise totally educationally neglected children in the Italian slums).
I think that whether the trade off is acceptable depends on the school's ability to finesse it, the parents' willingness to be flexible, and the particulars of the state and its bureaucracy. But experience is always useful because some things are universal so definitely I'd love to know more.
No FM today at all and I am really starting to feel under the weather. Bummer.