Go with your gut. At the same time, be ready for the school to fight you about doing anything. As you have already stated, according to them he is doing fine being at grade level. You are facing the 2e dilemma -- his giftedness may make it so that he is not disabled enough to qualify for an IEP and his LD (if he has one) may make a gt classroom not a perfect fit.
Your son sounds similar to my DD8 (without speech issues). My DD has been in a gt classroom since 1st grade. She always has read at or above grade level but needed a lot of support at home. She consistently has struggled with writing and spelling. At the end of first grade, we took her for IQ and achievement testing because everything seemed like it took so much effort. She was diagnosed as HG with dyslexia and dysgraphia. We brought this information to the school and were told that she did not qualify for services through school. They then gave an overwhelming number of suggestions for things that we could try at home.
We are in the process of doing vision therapy. I think that it is addressing some eye function issues that compounded my DD's issues. It will not change the fact that my DD's brain just works differently. Last year, my dd had a great teacher who was willing to work with my dd and give her extra time for writing. We still haven't found a good fit on spelling.
