I’ve been through this more in depth in past threads, so I’ll do a quick version here.
Autism isn’t about being afraid or repulsed by sensory input. Its more like an exposed nerve. There is no filter for that sensory input. If the sensory input is welcome and the feelings are good, then those with autism can find a level of joy out of that sensory input that those of us without will never be able to experience. The sheer exhilaration on my son’s face when he is "in the zone", is something I am truly jealous of. It’s a true emphatic joy for the stimuli he is receiving. The flip side, is he can’t shut it out. When it goes bad, when the input is unwelcome or something unpleasant, there is no suffering through it. It is like salt in a wound.
Those with autism that have a better time with that sensory input and more frequently enjoy it than not are called sensory seekers. Those who have more issues with it are called sensory sensitive. My son is a sensory seeker now, so WDW is a dream to him. But there are times when it gets too much and he will shut down and be inconsolable. But, the good times outweigh the bad (more and more as he gets older) so the bad is worth it for the good. Each person with autism will be an individual, and it is up to them and their parents to decide whether WDW works for them. As I have explained in depth in the past, we had a sensory sensitive child who came alive because of the over stimulation in the parks, so we used that to help him become more of a sensory seeker by using WDW as a therapy. It has worked wonders for him, and has helped him become far more capable of dealing with those stresses in everyday life. He still has his moments, but WDW has helped them become far less frequent.
So, to answer your question. Why would I risk bringing my son, to WDW? Because the reward is worth it. Not all tantrums are bad. Not all dissapointments, breakdowns, and crying fits, are a pure evil. We learn from them and grow. So, suffering through those early, have made him able to enjoy his favorite place in the world. He grew from those experiences, and can now enjoy WDW with limited break downs, and with now very limited use of DAS/GAC.