Guaranteed Interview Scheme

I am interested in hearing others' views on whether or not to declare one has a disability and then whether to tick the box on application forms that offer a guaranteed interview Scheme.  We always struggle when supporting our son to complete application forms, as we want him to have a fair chance, but equally don't want to raise his hopes by him being given an interview just because they have to and he meets the person specification criteria (which he regualry does) and then prospective employers not knowing how to manage his responses at interviews and deciding he wouldn't be suitable for the work.

I would love to see an alternative to the formal interview (and not just for people with Autism) perhaps where the candidate is asked to spend the day shadowing a range of people in the role, during which time the employers can ask pertinent questions of the candidate, but also allow them to judge the person in the capacity they would be working in.  Having spent many years doing formal interviews and the time they take up, I can't see that my idea would make the process any longer and would give a far truer picture of the candidate's skills and abilities. 

I look forward to others' thoughts and experiences on the application and intereview process.