One thing to keep in mind is if he is really ready for the accelerated math class. In our local gifted program, about half the kids go on to take accelerated math in 7th grade and half take the regular math curriculum.
The teachers told us that when parents place their kids in the accelerated math course over their objections, the child inevitably doesn't do well since he/she doesn't have the math skills to succeed. They said it sets up years of poor performance in math and loss of confidence in the subject. Just a thought.
In our gifted program, acclerated math leads to 7th grade algebra versus the regular course is 8th grade algebra.