It is interesting if you look at the data on this. Your advantage from Montessori school by third grade is well documented, but then you typically see that by high school the traditionally schooled kids catch up and the Montessori kids come back toward the average, even if they are still in a Montessori school. Obviously this all depends upon the individual child (which is, of course, a big component of Montessori philosophy) but statistically over a population, that's how it plays out.