I tend to be one who subscribes to the philosophy "If it walks and quacks like a duck, assume it is a duck". To me, the achievement, intensity, and logic you are seeing every day is much more valid than how he did on the WISC one day at age 8. Especially since you live/work with other GT kids, you know what it looks like. I'm sorry if you were going to use those scores for advocacy. Maybe you should do some achievement testing if you need scores? I think it is extremely unlikely you are deluding yourself.
Just out of curiosity, did your tester have GT experience?
