Andy,
Unfortunately, what you are expressing here is exactly the kind of stereotyping that the laws were designed to put a stop to. I have a colleague who gives a presentation called, "Of Blind mechanics and hemophiliac industrial arts teachers I have known." He says that, in truth, he has only known one of each, but it was enough to teach him not to make assumptions about what someone will or will not be able to do because of disability. You say that when you need a doctor, you want the best. Do you check out the medical school class rank of the doctors you see? Or do you assume that if they graduated from medical school, they must be capable doctors -- except, of course, if they have a disability and had accommodation in which case they AREN'T really capable. The argument really doesn't track. Are there things that people simply cannot do because of their disability? Of course. But if they have achieved the same credentals, then they CAN do those things, and to discount that achievement because of disability is just... wrong! (as my teenage daughter would say)
Dr. Jane Jarrow