There is NO state mandate for giftedness in MA. Each town/city decides whether to provide anything. Many times, nothing is done because they're not mandated to do so. A lot of us end up un/homeschooling as a result.
Hoagie's has a list of MA private gifted schools -
http://www.hoagiesgifted.org/schools.htm - my ds8 attended two of them, but is being un/homeschooled now.
With any of the private gifted or public gifted programs, it really depends on the child, the level of giftedness, the curriculum, teachers, other kids, etc. I don't think any of them cater to pg or hg kids.
A 2e child isn't guaranteed anything in terms of differentiation or acceleration either since there's no state mandate for giftedness; only a federal mandate for special needs and that's IF they qualify and their academic achievement is impacted. IF you have a high functioning, gifted Aspie who's a grade or so ahead, there's no guarantee you'll get ANY services.
MetroWest area of Boston - Acera is relatively new, being established less than 5 yrs ago. Birches in Lincoln was established 2-3 yrs ago. Bear in mind, though, MA's geography and the congestion because if you do not live relatively close to these schools, you're likely to sit in traffic and have a challenging commute.
IF you live in a town/city without gifted programs (like we do), there may be some ability grouping but it's very likely limited. Usually, there's AP or honors classes at the high school level, but usually nothing at the elementary level. As far as I know, children are expected to complete exactly the same curriculum regardless with the public schools and often with the private gifted schools as well; I ran into that issue with my ds with two of them.
In Mar (or perhaps Apr), I went to a MAGE (MA Association for Gifted and Talented Education -
http://www.massgifted.org/) Conference. There is NO state funding for giftedness and very unlikely to be any within the foreseeable future.
Beverly is on the North Shore and there's no g/t or any accommodation there. There are private schools in Beverly which tend to have some gifted kids and may make some accommodations.
Bedford is considered, or I think considered, within the MetroWest area. Their public school system has a good reputation.
Lexington is know for having a good public school system. However, it's also known for being a high-stakes, pressure cooker system. Tons of people from Harvard/MIT there. As a result, it's not a cheap place to live.
Concord-Carlisle also is a top ranking public school system. It has a reputation as being a little more granola or relaxed than Lexington, but it's also a very expensive place for housing.
Burlington is supposed to be improving their public schools and more digital friendly.
Waltham has a public gifted program and is cheaper to live in within the MetroWest area. I think it's only a couple of hours per week, but you'd have to check.
Framingham is further west and has a public gifted program, but again you'd have to check on what it entails. It's cheaper to live there though.