I don't have much information to offer you. I do know one neuropsychiatrist, and he rarely found work in the field specific to his specialty. The few times he did find work, it was often times in a VA hospital where he had to deal with those who suffered from head trauma.
It's common sense to believe that a psychaitry residency would make us good neuropsychiatrists. After all, we get trained in neurology and psychiatry right? We get board certified in psychiatry and neurology.
In my opinion, neuropsychiatry requires much more training than that. Why? I've rarely seen any psychiatrist know how to deal with cases of head trauma, specific damage to parts of the brain, or know that symptoms will be caused by damage to specific parts of the brain.
The guy I mentioned above did. Kluver Bucy syndrome, using psychometric testing, problems with executive planning, etc--he knew about it and how to deal with those issues.
IMHO, the need for neuropsychiatrists will go up because there are several soldiers coming back from the middle east with head trauma that would've otherwise killed them with the state of medical technology from years ago. These people will suffer from neuropsychiatric issues that the regular psychiatrist does not regularly deal with.
Unfortunately I can't give you much more information.