One of the most important things I've learned from this forum: if it makes your kid quirky but otherwise happy and functional, by all means call it an OE. If it's stopping your child from being the person they want to be, or accomplishing the things they want to accomplish, find help to remove this barrier to your child's well being. Don't worry about the label. For instance, whether or not your child officially has SPD, an SPD expert can help figure out how to deal with noise sensitivities.

"OEs" are a really fuzzy concept. So is the line between OE and SPD or ADHD or OCD, etc, all of which exist on a spectrum. What I've learned from this forum is just deal with the presenting problem. If your child is struggling, and it's happening in most environments, then a gifted program may provide a better environment in which to deal with his challenges, but it won't make those challenges go away.