My 2e DS10 did both the Cogat and WISC a couple months apart (a little under age 9). His composite and FSIQ were the same but his GAI was much, much higher. His scores are kind of all over the place on both tests. His GAI seems to be the closest match the kid that we experience.
Not sure if that is transferable to your situation though. He is probably the opposite of hyperlexia if such a thing exists. He was speech delayed, a late/average reader (until around grade 2 when something clicked) and his writing is still painful to watch (LD in written expression). He has sensory things but that seems to be improving with time. FWIW socially he's done much better now that he's in a congregated ~HG class. The only kid that he remotely interacted with at his previous school turned out to be also gifted.
