I apologize if this has already been discussed, but searching for "Basis" or "Basis Independent" yields a lot of hits for just "basis" or "independent"

MY DS7 is a 1st grader in a K-6 Montessori school which seems unable to challenge him. He is an extremely curious learner that wants to consume all knowledge ALL the time. He reads at 6th+ grade level and is near finishing Beast Academy Level 3. He has already started complaining about boredom at school and was moved to tears recently when he actually opened up about his experience at school.
We do have a BASIS Independent school in our town and have toured them. While normally, we are not fans of that type of a rigid curriculum, we have heard good things from people whose kids have gone there including from someone from the DYS community. The appeal would be the curriculum which we are told starts 1-yr ahead and runs at maybe at 1.25x-1.5x the pace of a regular school, such that by grade 6, kids are 2-3 years ahead. Seeing the pace of learning DS7 has demonstrated, this may still be slow, but a better fit than the Montessori option we have and definitely more than our public school options. Also, we were pleasantly surprised by the energy and enthusiasm of the teachers we met and saw on the tour of BASIS Independent.
On the other hand, our son has also been diagnosed with ADHD and definitely is NOT a linear learner nor a "good sitter"

. The BASIS campus we saw had classrooms organized almost like miniature college lecture halls with C-shaped rows facing the front. I fear this may be tough for my son, though I don't know for sure. But I do wonder if this means BASIS may be more geared toward the linear learner and good sitter type of student where a child, even though he can excel at the work, may get a lot of grief for not following the proper steps and do things in the correct order, etc.
Any thoughts or experience from the DYS community would be extremely appreciated!