Is your teen thriving in a SEND unit?
I'm contrasting a completely separate specialist provision (independent school) with a (more local) unit attached to a mainstream secondary.
I believe there are more students with similar diagnosis in the separate specialist. Finding your tribe is great but friendship doesn't require similar diagnosis!
DS's sensory profile means he's not likely to access mainstream classes. He's got a typical 'spiky ability profile' with areas of giftedness and needs a fairly bespoke approach.
I'd really appreciate hearing what's worked well for your teen.