First time replying, though I have been an unregistered lurker for years.
Let me say a little about our experiences:
My neurologically compromised DD and I first started going to DL when she was 8 years old. We were trying really hard to make our own adjustments, etc. We happened to run into a woman with a DD who had a seizure disorder while swimming at our hotel (trying to calm down and take a rest). This woman shared her story of their first trip and they ended up bagging the vacation and going home. It then she told us about a GAC and what a difference it was making this time around.
My sister and I discussed what kind of accommodations would work best for my DD. We went to City Hall (prior to CA) and received a GAC. We asked questions about the best way to use it and when to use it. It really bothered me at first and yes, we got some stares, but, I just figured it was the other person's problem and not ours. I made sure that my DD was respectful and courteous to the CM's. This was prior to the stamps so she needed to explain what accommodations she needed (alternative line, sitting up front, stopping the moving platform at loading, etc. according to the attraction).
It worked perfect for us, and there were times that we didn't even need to use it.
Over the years, both at WDW and DL, we have received a GAC. The last time we were at DL was the first time with the stamp. They just gave us an "arrow" stamp. That is appreciated, but, it doesn't meet all of my DD's needs. We still ended up explaining her needs according to which attraction. We have had very positive experiences, even a kind CM who explained to my DD that if she sat in the chair cross legged at ITTBAB she would enjoy it more. Visual distraction is a big thing for my DD and she learned to ask for the front or top row at Soarin' so she wasn't seeing the dangling feet.
At certain times, especially with new attractions, my DD has approached the CM and was given a time to come back. We absolutely love that! However, we were able to utilize the GAC on other attractions while waiting for our time.
The GAC hasn't been FOTL, but, it has been like a unlimited FP. At some attractions, we were moved ahead of some Guests who were waiting to board the wheelchair accessible ride vehicles. I had a nice CM explain to my DD one time that they could only accommodate so many Guests needing assistance on the ride at a time. This helped her understand the "why" to the waiting and greatly helped her.
Yes, this is a change, yes, it will be different, but, as I tell my DD, "Different is just that. Different isn't good or bad, it is just different." We will learn to utilize the
DAS, just as we learned to utilize the GAC. Yes, we will make mistakes and yes, it might not work perfectly the first or second time, or even the tenth time, but, we will learn from our mistakes. We will also learn to make the adjustments that will make my DD have a positive experience. When I say "we" I mean my DD and I. I don't expect Disney to understand my DD and to make accommodations for her. They are already making the accommodation by the DAS. Disney doesn't determine our happiness, we do. We plan on using the DAS and FP when we are at
Disneyland this January and having a GREAT time!
2tinkerbell
Hugs for everyone stressing about the unknown as much as I am! As someone else posted, GAC has never been a FOTL pass for us, but it did make planning our trip a lot easier and more worry free. I know DD will have difficulty with stamina and waiting for the return time to arrive. Using the time in between to "go to shops, grab a bite to eat..." doesn't work so well for kiddos who want everything scheduled and don't do well with unknowns. I can't make a visual schedule when we don't know the wait times or FP return times until that moment. For us, it will mean fewer rides/attractions and probably a few more meltdowns....but we're still 
