The tricky part of it is figuring out when giftedness, ADHD, and SPD occur together and when one thing is being confused with the other. For example, some kids with SPD are thought to have ADHD because the behaviors look similar, but the reasons for them are different. The same thing for gifted kids. But yet, some kids do have all three. There is some discussion that gifted kids have higher levels of SPD, although the data has not been collected to say this for certain. However, it makes sense with the idea that gifted kids experience the world more intensely than others.
If your DS has an ADHD dx I would suggest learning about the sensory seeking behaviors as well as the avoiding ones that you mentioned above. He may be exhibiting both, but the seeking behaviors are interpreted as part of the ADHD. I believe that SPD kids may often be misdiagnosed with ADHD by someone not familiar with SPD.
And for me, what is most concerning is how the child interprets the experience. If seeking or avoiding is such an intense need for them and they are constantly being corrected for it but not given effective alternatives, then they may start to think that they are just bad kids or that there is something wrong with them. But if we recognize their needs and find constructive ways to meet them with an appropriate sensory diet, then the world becomes so much more manageable for them.
It also gives you something to prepare their teachers with. So, at the beginning of the year I met with DS's teacher and explained some of his issues so she would understand where he's coming from and has some ideas of what to do if the sensory issues come up. His SPD issues include a lack of awareness of where his body is in the world and a need to "ground" himself by touching other people. So he bumps into people alot and sometimes invades personal space. Since I prepared the teacher for this, when he had trouble at the end of the day when all the kids crowd in to get their backpacks and coats, instead of seeing him as causing trouble she recognized the problem and allowed him to get his things first before the crowd hit.
I hope the OT evaluation gives you some useful info for your DS. And I will also tell you that OT is alot of fun and most kids love it! My younger son is SO jealous that his brother gets to go to OT!
