In my experience you may have to battle the "I understand his potential is X,Y,Z (based on SB5 and WISC) but his achievement is showing A,B,C (WIAT)" type of conversation. Prepare yourself for the arguement of potential versus ability. The broken record technique is helpful with that. If you look at his processing and working memory scores you will get an idea if they are going to bring up concerns with keeping up with in class material and homework based on those scores, but in all reality they probably still fall into the "average" range and shouldn't really impact anything. Gasp, a child can be GT and test "average".
If those scores are below average and in any way impact your son's performance in day to day class then you could ask for accomodations.
