We had a round of tests that showed gifted but not nearly as gifted as my gut told me. I was thinking maybe I was nuts, but Ruf's book gave me reason to trust my gut. We retested a couple years later, in part because of the confidence that that book gave me, and his scores were much higher than the first round and exactly where I thought they should be.
I agree with Kriston that there are problems with methodology and generalizability, but it provided me with an important reality check when I needed it.
