You've received great insight already from Portia.

In general, kiddos benefit from a stable, positive environment and having peers they can relate to with similar academic/intellectual ability, as well as one or more shared interests. Parents do not tend to change schools lightly.

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... DS's abilities are needing to catch up with the curriculum here so I'm not too concerned about his not being challenged...
Based on the information provided, rather than looking at schooling options you may wish to read up on advocacy for the day when having these skills may be useful.

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... researching educational options... switching schools if necessary... or other options
Generally speaking, children with more rare intellectual profiles may be the significant outliers for whom many learning environments do not provide a good "fit" as there may not be exposure to new concepts and material for these students.

As mentioned on another thread, the Davidson database is a great repository of information.

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I'm already a bit unhappy about how little science he's gotten over the year that he loves, the K math that advances so slowly and is so repetitive, and our school's obsession with testing, scoring, and the drill method.
While it's good for parents to be aware of the school's culture, many experts and experienced parents emphasize keeping the focus on the child's needs (rather than a parent's ability to imagine better circumstances).