sanne, I'm sorry you've had a poor experience with psychiatrists, but if you get a good child psychiatrist, actually my professional experience with them has been very positive. This all depends on getting a good one, of course. I would also say that there is a huge difference between a general or adult psychiatrist and a child/adolescent psychiatrist. In my opinion, I would rather involve a child psychiatrist than a pediatrician who specializes in ADHD (because if all you have is a hammer, everything looks like a nail).
I'm okay with dev/beh peds for relatively straightforward conditions, but really complex behavioral health concerns sometimes are beyond their skills. Again, this is very physician-dependent, as I've also encountered very skilled dev peds.
IOW, indigo's advice (as is so often the case!) is the key. You'll have to spec out the doc case-by-case.
