We have no stake in your answer. We work with children in both, and we say so here because the advice you get on this question usually comes from somebody who benefits from one of the two, which is worth knowing when you weigh it.
The framing that causes the most harm
Mainstream is routinely treated as the ambitious choice and specialist as giving up. That framing has cost a lot of children a lot of years.
A child sitting at the back of a mainstream classroom understanding perhaps a fifth of what is said, managing to be quiet about it, and coming home wrung out is not in a less restrictive environment. They are in a more restrictive one that happens to look ordinary from outside.
The principle worth holding is the most ordinary setting in which your child can actually participate. Both halves of that sentence are load-bearing.
The questions that actually decide it
What can this specific school resource?
Not what its inclusion policy says. What it currently does: how many children the coordinator supports, what training the class teacher has had, whether there is a quiet space that actually exists, and what happens on a day when the usual adult is absent. Ask to visit on an ordinary Tuesday rather than an open day.
What is the child's day actually like?
Ask them, if they can tell you. Watch what happens at 4pm — a child who holds it together all day and falls apart on the drive home is doing an enormous amount of work you are not seeing. That effort is a cost, and it is being paid whether or not it appears in a report.
What is being learned, and what is being endured?
Presence is not participation. If your child is in the room but not accessing the curriculum, not being taught at their level and not part of the social life of the class, the placement is delivering the appearance of inclusion rather than inclusion.
What about friendship?
This is often the strongest argument for mainstream and it deserves to be examined rather than assumed. Does your child have friends there, in the sense of children who seek them out? Sometimes the answer is a clear yes, and it settles the question. Sometimes proximity to peers has not produced peers, and a specialist setting produces more genuine friendships than a mainstream one ever did.
The options between the two
It is rarely a binary, and the middle is under-explored:
- Mainstream with genuinely resourced support, properly supervised and reviewed
- Mainstream with part-time withdrawal for specific teaching
- A specialist unit attached to a mainstream school, where that exists
- A specialist setting with a written plan to return, which does happen
- A different mainstream school — schools vary far more than categories do
That last one is worth taking seriously. The gap between two mainstream schools' capacity to include is frequently larger than the gap between mainstream and specialist in the abstract.
How to decide
Write down what you want your child's ordinary Tuesday to look like in two years. Then ask each setting, specifically, what they would do to produce that. The one that answers in detail is usually the one that has thought about your child rather than about admissions.
And remember it is reversible. Children move in both directions and it is not a failure either way. The decision that is genuinely hard to undo is spending three years in a placement where nothing was working while everyone hoped it would settle.