Although I agree that it is a good sign that the behaviors rarely occur outside the home, I would still be a bit concerned about cyclical episodes of 10+/day for a few days in a row. Even if it turns out to be sub-clinical, whatever is going on still affects your home, your relationship with your child, and your child's perception of himself (since he clearly knows this is not expected behavior in general).
I would also agree that a naked IQ test would not answer the primary questions you are asking. I do not, however, think that a neuropsych would be overkill. Regardless of the specific data, you will receive valuable normative and clinical information about your child. If the outcome is simply that this is within normal limits, and you should just keep doing what you're doing, and wait for him to solve this developmental problem on his own, then that should relieve some anxiety, which certainly has value. If the outcome is that something should change about his setting or interventions, then knowing this sooner than later can spare him and you quite a bit of future distress.
