The fact that this teacher took the time out to write such a lengthy e-mail specific to your son's situation would make me want to at least have a conversation. Especially if you have any doubts at all about the Montessori. Anyway you can stall your meeting at the Montessori to have the talk? Does not signing now mean you'll lose your spot? Would it be reasonable to talk to your DS and see what he thinks, or wouldn't that work at your house?

That's a tough one! Good luck and keep us posted!