To answer the original question, yes, I'd totally have him tested. You'll just drive yourself batty wondering, if you don't. But make sure you find a tester who has experience with highly gifted children. FWIW, though, keep in mind that test scores at age 5 might or might not be totally solid. My DD's tests around age 5 were firmly in the moderately gifted range even though she was a little uncooperative, which seemed totally satisfactory at the time. Her scores at 8 were considerably higher and explained a lot about her hyperachivement.
