I think you really hit on something with the "regress at some point" idea. Our youngest daughter has severe (low functioning) autism. Starting around 1 year old, her behavior and language seemed to start regressing (she was talking in 3 word "sentences" prior to that). At first, we had a "diagnosis" of Pervasive Development Disability - Not Otherwise Specified (PDD-NOS) before officially getting one of actual Autism. It has taken years of therapy (ABA), and many doctor visits (I assume MIND institute refers to UC Davis Med Center MIND..., which we've certainly been to) to get her at 10 years old to function at roughly the level of a 3 year old.
That regression seems to divide the Aspergers from the hard-core Autistics. Our son has Aspergers, as well, but is quite intelligent. Getting him to shut up about his own little world can be a challenge, though. He is learning to cope, and dealing with his issues is far preferable to low functioning autism. (unless of course one likes having ones house tore up most of the time, "potty breaks" in random spots around the house, and trying to keep a child from running out of the house who may or may not be dressed...)
That regression seems to divide the Aspergers from the hard-core Autistics. Our son has Aspergers, as well, but is quite intelligent. Getting him to shut up about his own little world can be a challenge, though. He is learning to cope, and dealing with his issues is far preferable to low functioning autism. (unless of course one likes having ones house tore up most of the time, "potty breaks" in random spots around the house, and trying to keep a child from running out of the house who may or may not be dressed...)