My daughter can be lifted out of her wheelchair (so a not easy transfer), but stays in her chair for any attractions that have a wheelchair accessible vehicle.
We’ve been coming to WDW for many years and used
DAS (and the Guest Assistance Card it replaced) because of her other needs.
The issue with the waiting area itself being crowded or small is more of an issue with some of the older attractions. Newer attractions and many of the older ones that could be updated have the handicapped boarding area moved closer to the ‘regular’ boarding area and have a pull off point separated by ropes for guests with special needs to wait.
We’ve found our waits in the dedicated boarding area or line for most attractions has actually decreased a lot since DAS started.
Before DAS, we usually waited for an extra 15-45 minutes in the wheelchair accessible boarding area for Toy Story Midway Mania. Why? Because people with Guest Assistance Cards with a stamp to “use alternate entrance” were also using that area. At times, there were only 2 groups out of maybe 8 with mobility devices and the line waiting there extended all the way to the end of the ramped entrance to the area. Now, we are sometimes the only guests waiting and get on as quickly as the wheelchair accessible vehicle (WAV) arrives. For that particular attraction, the extra track without stairs made some difference, but the biggest change was limiting that access area to people who actually need the WAV.
We‘ve seen the same thing on Small World. Before the change, the wait usually went up the ramp all the way to the exit, with the majority not using a mobility device. More recently, we’ve had at the most 2 groups in front of us.
Jungle Cruise made a change in the past year - the waiting for guests with mobility devices has 2 areas, with a rope between them. One is for those who can transfer and the other is for those waiting for the WAV. They may not always have the separation, but in out trips in the past year, they hs d.
The one that still has a long wait is the Safari. It’s really variable though - we’ve been in line with several guests using wheelchairs ahead of us and thought they either would all transfer and they didn’t or thought none would transfer and they all did.