I obviously am going to feel the "user" has a better understanding than the "provider", you feel the opposite.
No, that's not what I am saying at all. What i am saying is that, for any given child, the best education setting (even at the broad brush level of HE / MS school / SS) varies depending on the child, their needs, the specifics of their home life, and the specifics of the SS and MS school involved.
I am quite happy to agree that it is entirely possible that the SS that you chose for your child was not a good fit for them, and was, for them, a worse choice than an inclusive ms school and HE.
I am not quite sure why you feel I cannot say that, knowing the specific child, their specific home life and therefore HE available, and the MS school and SS involved, the SS would have been the best option FOR THEM.
You seem determined to say that SS is never the best option, for any child, regardless of disability or any specifics of home life or MS school, and thus the only options for any child with any level of SEN are MS school or home ed. This seems to be based mostly on your own experience and the experience of others who live locally to you. With SEN being such a vast field, with so many variations in kind and degree, and SS being highly varied in their provision and support, I am not sure why you feel there cannot be any possibility of different opinions being formed for different children in different settings.
I suppose I had seen the difference between us as being 'caring for the needs of different children, in different geographical areas, with different home lives and different needs', much more than as 'parent vs teacher', which you seem to see it as?