My son can also be quite the gentleman. He has picked these clues up from watching other people, TV and movies along with reading a wide variety of fiction. That doesn't mean he really is able to take my perspective - he's imitating behavior he knows he's "supposed" to display. I'm not saying that's the case with your child, just saying it is true for mine at this point.
I agree it can be hard to figure out and sometimes you need to decide why you want to figure it out. If your child is going to public school it can be essential to get a diagnosis that the school understands and recognizes. Unfortunately, being "odd" doesn't get you services, just lots of negative attention.
I have long wondered about whether my son was on the spectrum but his language skills are so superior that he dazzles most adults. I have been told repeatedly that my child is "a little professor". Trying to get his doctor to listen to me (or even the school psych's) has been an uphill battle.
I do think that ASD kids can learn and change their behavior. But that doesn't mean that the underlying difficulty has disappeared - it just means they have adapted and learned the rules of proper behavior. It may be that your child was mis-diagnosed or that he is on the spectrum but not as severe as his earlier assessment suggested.
I know my son's problems have only become really prominent in the past 2-3 years. He had symptoms before that (including the whole parroting thing when he was little) but the social difficulties didn't become really noticeable until he reached 4th to 5th grade. And because he has a hearing loss, some of the problems he has were attributed to his hearing loss.
Since your child is 11 I would really consider getting an updated speech eval. And if you're not doing much writing to grade level prompts you may want to focus on this as a way of helping clarify whether he really has problems with perspective taking. For my son, the impact of the ASD issues is really apparent when he tries to write a response to literature that requires him to analyze and respond to human emotion or social interactions. He also has trouble writing from his own perspective - if the writing prompt asks for him to write a story about his own experience he usually ends up writing about someone else as the main focus of his story - instead of himself.
Patricia
