In my experience the more qualified a mental health professional is, the more likely they are to be a self aggrandizing pompous prick. I have found the most helpful practitioners around DID issues are the ones who know very little about it but are open to educating themselves.
And the whole diagnosis thing is just flippin annoying - I understand that sometimes a label is needed because that is how the funding / insurance system works, but a treatment system based on a diagnosis is a flawed one at best. All a diagnostic label does is describe a particular set of symptoms. But a human being is so much more complex than a 'particular set of symptoms'. In fact a human being is never made up of any one particular set of symptoms - they often don't have all those symptoms and nearly always have many symptoms that rightfully belong to other labels too. If we took all the labels away, we would still be left with human beings who have the same unique set of symptoms that they always had.

Wouldn't it be much easier to simply meet with a human being, get to know them, and then help them find ways to lessen / manage / heal the set of symptoms that they have? Wouldn't that work so much better??