It's only one or the other, not both. We just sent the WJIII achievement test results, no IQ test, along with a portfolio of work, and he was accepted.
I had to laugh at your reading comprehension comments--I've kind of had to go the other way with those remarks, with DS6! He showed a 9th grade overall reading score, with post-college level "word attack" scores, and 2nd grade comprehension, when he was 5. They said, well, see, he's not comprehending everything he reads. I said yes, but he could have gotten those ability scores two years ago and he would have had NO comprehension at all--comprehension is coming along, and after all you have to be able to read something before you can comprehend it!

With no life experiences, comprehension comes harder than being able to read things. It's only as we gain experience that we start understanding more and more. Give him time!