RE: the September 30 cutoff.
When I was growing up, the cutoff was 9/30. I was born 9/16, so just made it. I almost wish that my mom had held me back. Academically, I was advanced, but socially, not so much.
Out of a graduating class of 700, I was always in the youngest 10. It's hard. I graduated at 17, and there were kids in my class who were turning 19. That's a huge social difference. Many of my friends were in the year behind me, because that's who I more closely matched agewise.
Just something to think about.
Re: REOM
It really is a tough call. My H thinks I am crazy for already stressing it.
My sister was in the same boat as you, only my mom held her back. The majority of her friends were in the next grade anyway, and she always wished she was in the higher grade.
My bday is 10/13, and the cutoff growing up was 10/15, and my mom also held me back. Socially I was fine, but academically, I skated. I don't think this was entirely good b/c I never really learned how to study, b/c I didn't need to. It was quite a wake up call when I went to college and had to teach my self study skills in the midst of a huge adjustment. I wonder if I had been challenged at a younger age if this would have been different.
I just wish the decision wasn't mine to make, b/c I will feel responsible either way. If that makes any sense.