My ds had the WJ-III Cog + Achievement testing through school, and although I'm not sure how long it took, I know from what he told me that he missed the full morning of school, which would have probably been around 3 hours.
I would ask for the full report with subtest scores, and I would also ask what order the subtests were administered in - that way you can look for red flags such as noticeably lower scores on subtests toward the end - which might be an indication of your ds being tired or bored or hungry etc.
The other thing I'd consider - if the testing stretched out to 3.5 hours, it's possible that part of the reason was the tester gave your ds short breaks between subtests. When our kids have been through neuropsych testing they are tested for 3 hours morning + up to 3 hours in the afternoon on the same day, but they are given frequent breaks for water/snack/to get up and run around etc.
I am guessing the scores you refer to above are percentile scores (97 and 98)? A one-point percentile difference might be nothing more than standard error of measurement. Will not having the gift id hurt your ds in any way? Are there gifted programs he won't be able to get into? If it isn't a number that he "needs" for anything right now, I'd get the report, take a thorough look at it so that you understand it, and then move forward as you were before the gifted testing happened. If it *does* mean he won't get into a specific program or whatever, I would think that you most likely have a strong set of test scores and a circumstance (sub-optimal testing conditions, tired, etc) to at least appeal that he may very well be a 98th percentile kid. There are also different ability tests available that he could be tested with as an alternative if you are interested in seeing if he could score above a 98th percentile. Please know I'm not a testing-happy-fool lol! But if you do test under a circumstance where the tester isn't rushed, testing is often actually fun for a lot of gifted children.
Best wishes,
polarbear
