I don't have much to offer in terms of why the scores might not match the child, but I have one child who sounds a lot like what you are describing and who had very similar WISC-IV composite scores to that at seven. She did have a lot of scatter within indices, though, such as an 8 and a 19+ in the same index. Did the tester mention whether his scores were consistently around the same spot or if he was uneven? I understand that kids with really high highs that are pulled down by other much lower scores might be more gifted than the composite # indicates.
FWIW, mine will be 14 in about two months and entering 10th grade. I, too, have had many, many teachers and others tell me that she is the most gifted kid they've ever worked with and she, too, stands out as tremendously different than MG kids.
I've been comfortable accelerating her more than her IQ numbers might indicate for two reasons: she fits better educationally and socially with this older group, and our local GT programming serves about 20% of the kids so even a 98th-99th percentile composite kid is fairly different from a kid who hit the 95th in one area once after test prep, repeat testing, etc.
