Totally understand where you're coming from. My DD was in a Montessori-based daycare until she turned two, and then went to an actual Montessori school. In fact, she'll be finishing her third year at the school next week, and will be starting a new school in the fall. It took her a few weeks to adjust to the regular Montessori school. I have a feeling that the transition in the fall to a new school will be the same, but we think it is best for her at this point. I really do think it was harder on DH and I than it was on her. It is hard to imagine new bonds being formed (with teachers and friends) when the old bonds were so strong and valued.
Good luck with the transition and welcome to Montessori!
Thanks CatsCradle for the kind words!
Just got to work after dropping her off. Spent about an hour with her to help familiarize her with the new school. It was really hard to leave this morning, but I'm so excited that she is starting at Montessori. I think it's going to be so good for her :)