Pretty much exactly what we have been thinking-- and also what all of you have been saying as well. I guess we're all on the same page. It just seems like it might not be the same one that we're on with our local mental health professionals. <sigh>
Have you met with multiple people or just to the office staff of this one ADD doctor? I would not discount the ability of local providers to help until you've done a lot more research.
Trying to say this gently...I would encourage caution about not dismissing too many options too quickly. It can be easy when you are feeling worried and protective to believe that nobody will understand or help. That can become self fulfilling prophecy. If you don't like the ADD doctor of course move on, but I would not be dismissive of the possibility that anyone local could help you. An 11 year old sneaking the computer and staying up late... that is hardly a rare problem that only a few could understand.
Also, I don't know if it is reasonable to dismiss anyone who wants to do testing. If you believe that giftedness likely plays some role and seek out people who believe the same many will want to do that sort of assessment. You mentioned concern if the school saw the assessment, but I'm not sure why that's a worry. This is a private assessment right? You aren't obligated to share that information with anyone you don't want to.