Welcome jt,
Put us in the group with triplejmom, where the WISC scores were higher than RIAS. I also agree that may have had something to do with the testers, as the reason we had the WISC done was because the RIAS appeared obviously off and not representative of our child.
I'm curious about the testing you referenced at UF? Gainesville? Do you know if the testing was conducted by students or was there some other tester? I will caution that I've heard from several folks, including some on this board, whose children were tested by students not familiar with HG+, who felt strongly that the results were not representative of their child. If your WISC and achievement scores don't correlate with the RIAS, you may have the opposite problem with inexperienced testers.
If you don't get any assistance from UF, I can PM you with contact info for the psych who did our testing in Gainesville and she may be helpful with local info and guidance. I know of at least one other poster from this board who is local to you, who might be able to provide you local specific information. We are nearby, but not exactly local. Although we have close ties in town, our personal experience is a different school system.
I understand your concerns with the emotional and social concerns. My DD (now 9) had similar issues - highly emotional, intense OEs and struggled with those through K and 1st. Not the same size issues, although those are becoming more pronounced now. We skipped 2nd and she is now getting ready to enter 5th. Last year, we still had problems with meltdowns and frustration, but I've come to realize this is how she is. She's been this way since she was an infant and she will be this way when she is a teenager. She will have those issues regardless of how old she is when she goes through any particular grade.
I will say that having the opportunity to learn at something a little closer to her readiness level in the accelerated grade mellowed the OEs, at least for a little while. The first 2-3 months when she accelerated into 3rd grade were the best educational experience she's had. On the other hand, you mentioned that your school is already doing some subject accleration - that may be a better way to handle it if he can learn at or near his level in some subjects while also having opportunities to work on the handwriting and other stuff in a first grade class.
We did the full grade skip because there was really no other option and we decided the cost of not doing the skip was worse than the cost of doing it. That evaluation is different for everyone.
Good luck!