The gifted preschool sounds at odds with the current thinking on early childhood development. If the Montessori allows for materials to be brought in from the older age classrooms or for visiting them, I'd try that instead.
We really liked Montessori, when it was a good program that had some flexibility in it. It was wonderful for our PG child, who was allowed and encouraged to follow his interests, including learning all he could stretch to learn.
All of this! When I was looking at preschools I toured a few who were really proud of their worksheets and homework. Oh, my!
Both my children attended and loved Montessori preschools. They both progressed quickly through the curriculum, even though the per-enrollment speeches always sound like your child will have to do so much drudgework before they learn anything. But really, it was fine.
I think the key to a good Montessori experience, however, is having a really solid Montessori teacher. A Montessori classroom should fell orderly and purposeful, and should stress real-life competency activities along with more academic stuff. I always say the 2 top things my son learned in preschool were phonics and how to safely slice vegetables with an actual knife.
