We were there Thanksgiving through the first weekend in December, and we got the
DAS for my husband- he has Crohn's. After a disastrous start with trying to use our FP+ (basically we weren't supposed to have them was the conclusion because we were AP holders but weren't staying on site- whole separate post), we got the DAS- first time using any of the systems aside from FP-.
He waited his turn in line at GS at Studios (this was after having to bolt twice while waiting for the FP+ members to attempt to fix our MBs), and explained that he couldn't wait in lines because he had a condition that would cause him to leave quite suddenly, and that he didn't have a lot of stamina. The CM had him sit down, then filled in his info, took his picture, went over the pass, and boom, we had it.
We used it in combination with FP- because that was all we had, and were able to ride Toy Story Midway Mania for the first time- we got a return time that was an hour out, then rode ToT with fast pass, then sat in the ABC Commissary for a bit, and then enjoyed the animation studio for a bit so that he could have AC and shade before riding.
We did the same at Epcot with Test Track and Soarin'- since his mornings can be unpredictable and the FPs are going so quickly we had planned to use our FP+ but nope, so we used the DAS instead, and found shade. We were even allowed to use the back entrance to Star Tours once because he didn't think he could make the queue.
We didn't have any problems, any questions, or any nasty CMs. We had nasty GUESTS staring about the pass, but that is their own problem.
I'm sorry if anyone has any problem with cast members- I definitely can recommend going to the Studios to get theirs.