Pearson is working on the extended norms. They were anticipated earlier this year, but it looks like it will be longer, based on the research update from March. I would think the extended norms would be valuable for your DC. The likelihood of hitting the absolute ceiling (max raw score) on the WISC-V is quite low (though it is possible), because one not only needs to complete all of the designs accurately, but also quickly enough to obtain all bonus points for every item. If he did, the extended norms would be quite interesting.
http://giftedissues.davidsongifted...._Extended_Norms_data_col.html#Post231489As I mentioned upthread, I don't think I would worry too much about the low Symbol Search score (not normatively low, BTW, just in comparison to his other scores; 25%ile is considered within the average range, certainly not way below median). His Coding score has to have been respectable to net a PSI at the 63rd %ile.
Also, I would reiterate that, though your examiner may be a competent and knowledgeable professor, that was not a standardized administration of the subtest, and is almost certainly a low estimate of his actual skills on that type of task. (Honestly, it's the kind of small administration error that someone who only does a handful of evals a year might make--not having done sufficient volume to see the children who will stop to erase if there is even a tiny vestige of an eraser, or who will panic if they change their minds and don't know how to indicate the correction. Your examiner may be very experienced and well-regarded, but it doesn't mean they are flawless. I certainly am not.)
The plethora of test observations reported by the examiner strongly suggests that this result does not mean what it usually would be expected to mean (regarding speed); that is most likely why the examiner is reporting them--not to say he has a weakness in speed, but to say he does not.
