Our experience: DD(now)14 has taken the Explore and ACT through Belin-Blank and has taken the ACT and SAT for Johns Hopkins University - Center for Talented Youth (JHU-CTY). In my opinion the tests provided valuable information in filling out the picture of where our daughter was/is at. Combined with IQ testing and school achievement tests, we have been able to confirm, with hard evidence, what our gut was telling us about her talents.
I wouldn't hesitate doing a test over concerns the score may hinder your son. A bad score will keep him out of the talent search, but so will no score (ie not taking the test). And if he bombs the test this year, and aces it next, the talent search will only really care about the second score.
Also, if you don't share the score(s) outside of the talent search, there is no way it will be a hindrance anywhere else.
Best of luck,
--S.F.
