Yep, interesting article. It looks like there is better agreement on diagnosis of ADHD, than the more difficult bipolar diagnosis. Then there are the co-morbid conditions blurring the lines.
Kind of reminds me of the early mis-adventures in PMS diagnosis. That was also a mixed bag for diagnostic purpose based on symptoms that come and go. That was even after the whole issue of whether the simptoms were real or just in our heads.
Article on Psychiatrists disagreeing on diagnosis in children.