This is a message I wrote on the Oz-Gifted list responding to an inquiry about the Montessori methodology and how appropriate it might be for gifted children. I have published it here until I find something better in the hope it might be of value to others.
I had hoped someone else with better information might respond, but as I haven't seen anything I will have a go.
Our two started their formal education at a Montessori preschool and with our oldest the local Montessori primary school was on our shortlist (this was about the time we discerned that he was gifted and that this had some ramifications for choice of schools!).
Montessori has a strong element of flexible progression with the ideal being a child introduced to "materials" when they show an interest in them and are ready for them - ie on an individual basis. There is also a strong emphasis on whole education - from how to make a bed to picking flowers to washing and ironing their lunchtime napkins.
But there can be shortcomings for the atypical child. The Montessori program of indvidual progression assumes that there is one order of progression and may not be flexible in the case of a child that does not fit. Certainly a great deal depends on the flexibility of the directrix (as in any school) and their preparedness to balance the philosophy of the movement with the particular circumstances of the child.
In our case the directrix was also under pressure to ensure that those leaving the preschool (at age 6) had the basic reading and writing skills, and saw fit to require all her students to undertake writing drill. This proved a problem for our son who had also outgrown the preschool's materials about half way through the year. When his outlet of reading was removed as an incentive to do the writing drill, well the problems escalated rapidly and we removed him half way through the year.
This didn't stop us sending our daughter to the same preschool and being basically happy with it.