As someone with an ASD and a user of the RAP system, I can say that the system is very useful.
I find sometimes that if a plan is off by a few minutes, it can incredibly stress me out (the M25 really got on my nerves when it clogged for 20mins). I find sometimes certain noises can annoy me, imagine that in a large queue? Due to a few bad experiences (unrelated to theme-parks), I find that I am quite a paranoid person. At parks, I often find myself nervous as I feel that someone I know (and usually don't get along with) is nearby (as parks are very large, public places- anyone could be there at any given moment). In a queue, this feeling would be horribly heightened.
Luckily, I haven't seen anyone give me dirty looks (I think I might have got one when walking down Smiler's disabled entrance with a full cattlepen), but it is disgusting that such a thing happens.