The gifted program isn't a pull out program but rather is an actual gifted class with only gifted kids in it. So they have 2nd/3rd graders together, 4th/5th, and then 5th/6th.
So an actual gifted class is better than a pull out program, but I would try and spend some time observing the 2nd/3rd graders in the gifted class. You might be delighted or upset - only way to know is to watch.
With a kid that gets cranky without stimulation, I would be sure to ask early on for accomidation. I remember being very perplexed at Math for Kindy and 1st grade. I had no idea that my child was 'different' and couldn't imagine why they gave such elementary stuff to the other kids. But slowly I began to see that the school wasn't being mean or misguided. My kid was on his own developmental path was all.
Smiles,
Grinity