I am going to have to be brutally honest here...*but in the most positive sense*
I live life with 2 children on the Spectrum (and others in the family). There are not alot of people in this world that would ever understand our needs, unless they walked a day in our shoes. I am well aware of the misunderstandings from others, as it is not a "visable disability", but this was also true within our own family.
We had to really warm up to the idea that our children had unique needs, that they were simply overwhelmed by various things that were no big deal to others, had unpredictable responses to sensory stimuli and often resulted in hard to manage behaviours and meltdowns.
It took a while to truly "accept" that this was a "disability" and stop expecting "normal" everyday happenings...as our lives are so unpredictable from moment to moment.
There is absolutely no shame in making use of the GAC for your childs needs.
To be completely honest, we never would have been able to return to Disney more than once if we didn't have this accommodation. I am sure it would have been the most miserable time and well, the GAC more than tripled our experience there.
It is the reason that WDW will get our money, year after year. They really do take care of their guests and you should not have to feel guilt for something like this. We have enough to contend with in our daily life, let your vacation be free of stress, misunderstanding and judgement.
We are an extremely active family. We go from morning 'til night if/when possible and WDW made no mistake in allowing us the freedom to enjoy ourselves when offering accommodation for our repeat visits.
We have never been made to feel uncomfortable.There has never been a question or odd glance. People just seemed more sensitive and more accommodating. We have even had accommodations made that allowed our daughter (who has anxiety) to skip a particular bit of an attraction and was placed directly onto a ride, so that we didn't get through a line-up to find that she couldn't cope and ran screaming back down the aisle in fear.
Now that is DISNEY MAGIC!
I have had one person (another guest) ask why we were entering through another door, but I just casually said our child had special needs and carried on. I was a bit annoyed at the fact that I felt pressured into divulging that sort of information, but her question wasn't malacious in the least. She just wondered if she was in the wrong line...
I say, go for it! You won't find anywhere else in the world that is this sensitive to our needs. Enjoy!