As for Montessori... sometimes it works out great for gifted kids, and sometimes it works out badly in spectacular ways. It mostly seems to hinge on the personality of the child. Gifted children who possess the traits of silliness, creativity, and independence do not take well to the emphasis on structure, where every work has to be completed properly before moving on, and each can only be used the way it was intended. If that describes your child, I'd suggest looking at other options.