The new classification is actually better in my opinion. I have a child with Aspergers and I think it eliminates some of the confusion that surrounded the diagnosis previously. Children and teens need neuropsychological testing done for a definitive diagnosis of an autism spectrum disorder. For an adult it's probably not as important to be tested unless you are in need I disabity or other government services. Quite honestly the testing for ASD is done for more beurocratic reasons than anything else (as it also likely is for ADHD). But if the diagnosis is for your own information and for developing a treatment plan then a dx by a therapist with expertise in this area (experience is very important here) is fine and can be very helpful.