I would think "fitting in" could be an issue for a fair amount of children.
This was true last year for our DS, because the differentiation (ex. reading higher level books for assignments) meant he didn't get to do the reading aloud with the class, etc. In a different school this year, it seems less of an issue, but the main grade teacher does a lot of small grouping/individual work with all kids and also pullouts seem to be very common for all types of students. Thus, it's not that "different."
In class, he gets different spelling lists and related assignments. They all get to do computer-based learning for a portion of the day, his just happens to be more advanced.