It sounds like the reasons for considering a school move are spotty curriculum and inconsistency in providing accommodations? You may wish to focus on these things when looking at the other schools.
Option 2: Are parents able to make a placement at the public school you like? (Placement is not precluded by a wait list, lottery, cutoff date by which to register intent to enroll, etc?)
Option 3: "Might be more flexible regarding accommodations..." MIGHT is a mighty big word.
You may wish to ask about accommodations ahead of time such as on a school tour. A pricey school being able to "handle" gifted kids may not mean meeting gifted/2e academic needs and accommodations.
Based on the information in your post it sounds like ds' interests and learning style are a good fit with Montessori.
It is great to be prepared with lists of questions to compare each potential school. The questions to ask when seeking information that will help predict a good educational fit may be different for each family. In general, when selecting a school parents may want to ask about:
1) anything that you have been trying to put in place in your children's current learning environment,
2) details for anything described on the potential new school's website,
3) anything mentioned or observed during the school tour.
A parent may wish to consider their children's current learning experience and ask questions that would help them compare/contrast how the students' learning experience in the new school would be the same/different from what they have now. For example: How are children grouped for instruction? Would it be easier to advocate for having the child's needs met at the new school?
There are more ideas in the book "A Parent's Guide to Gifted Children", which has Chapter 14 dedicated to "Finding a Good Educational Fit".
There are lists of considerations and questions for choosing a school found online at Davidson database, greatschools website, and other websearch results.
Good luck with this.
