I'm sure that selective colleges are smart enough not to hold 7th grade scores against applicants. I suggest saving the scores. Since the SAT is a low-ceiling test for the gifted, especially in math, his 7th grade math SAT scores may be more informative than his 11-12th grade ones, which will likely be be close to 800.
I thought about this some more. Selective colleges won't reject applicants based on mediocre 7th grade scores, I assume, but there is another consideration. Innumerable articles have (wrongly) stated that "privileged" students do well on the SAT in 11th-12th grade because of expensive test prep. Seeing that my son had a high SAT math score before age 10 and an even higher score at age 17 could be interpreted as his being prepped for the SAT for more than 7 years. (It's actually things like the AMC that we are preparing him for.)
If I were an admissions officer I would keep in mind the studies of the predictive power of high 7th grade SAT scores
(for example "SAT Exam, Taken at Age 13, Can Predict Career Path of Gifted", by Matthew Keenan - September 7, 2007,
http://www.bloomberg.com/apps/news?pid=newsarchive&sid=aCVwvI2U53.Q&refer=us ) and prefer candidates with early high scores, other things being equal. But my views are not universally shared
.
I'll present the pros and cons to my son before 9th grade and let him decide, but I'd still lean toward keeping the scores.
