Welcome lys! I can't help re Philadelphia, but I'll bump for you.
I will say: be sure not to let giftedness be a reason to dismiss behaviour issues. Typically 6yos don't spend much time doing tests etc.; it would be surprising if your DS literally having nothing to do were much of the reason for the teacher's complaints. Even if his behaviour is in some sense justified, it's a lot easier to get accommodation for a well-behaved gifted child who is liked by his teachers than for one who is considered a bit of a nuisance, I think, so it's worth paying attention to.
