Yeah, check it out. We have a lot of parents of older kids come through wishing they had done more extensive evaluations when their kids were younger. You'll be much more equipped to make decisions on treatments by having a big picture than through a short evaluation.
Also, just to let you know, whenever we hear of young children who are having big time social problems we encourage parents to familiarize themselves with signs of Autistic Spectrum Disorders. The lower functioning (nonverbal, non interactive) children are obviously picked up pretty quickly but the higher functioning kids can easily slip under the radar. You would be looking for things such as avoiding eye contact, lining up toys or other household objects in straight lines or formation, speech delays or conversely more advanced, adult sounding speech, really obsessive interests--often not typical of their peers, overly sensitive to sensory stimuli such as lights, loud sounds, food textures, clothing, etc.
It would be good for you to pick up a copies of two books: The Explosive Child by Ross Greene and What Your Explosive Child is Trying to Tell You by Douglas Riley. Also, check out the thread at the top of this board on The Explosive Child.