Thanks everyone so far. Lots to consider here. I have my first meeting with a parent in the district TAG program tomorrow. I knew I would get great answers here!
My son has a 504 due to his Generalized Anxiety Disorder. For him it is not merely a need for acceleration, but his anxiety is genetic. Moving him to a higher challenge classroom would not alleviate his anxiety. The 504 gives him extended time on tests and enables him to take breaks when needed throughout the day.
His processing scores were 9th percentile based on the WISC IV. When we finally got him privately tested, he fell apart whenever there was a timer. The district does not recognize slow processing as an issue (it is not part of the DSM) and therefore he has no accommodation for that.
I am working on getting him extended time when he takes the NNAT2 based on his 504. No confirmation from the district yet.
Indigo hit the nail on the head regarding concerns I have. He is a very slow worker in general, so we are concerned about the amount of homework and the pacing of the TAG program. Is this for hothoused kids who love work, or for truly different learners? I haven't been able to get to the bottom of that yet. I just don't want to throw my son from one bad environment into another one.