I think the key word is "wants." Since this is your DS's choice, I'd let him participate as long as he seems to handle it well. We offer the AMC 10, and we have more seventh graders taking the contest than students in other grades (45% 7th graders, 36% 8th graders, the remaining 19% split evenly between 9th and 10th graders.) One of the reasons we started offering math competitions is to offer gifted students the chance to really challenge themselves. Challenging competitions have helped my DD with her perfectionism. When she does do really well, she's truly proud of herself because she actually had to try.
