Mayjay - sincere apologies for hijacking your thread - didn't mean to rant!
Your DS sounds so similar to mine. After years of wondering and waiting for him to grow out of the behaviour, I think I've finally pinpointed what's "wrong". I think he has some firm of anxiety disorder. The controlling behaviour, tantrums, anxiety and rigidity all fit. There can be a cross-over with Aspergers but this isn't always the case.
I found this really good website: www.anxietybc.com which describes this and sets out strategies to help. From what I gather they also need professional help. It's still probably worth a trip to the GP to refer for assessment for your DS - I did.
Does this fit with your DS?