J.R.
I was the bright child who started kindergarten early, and although I never had a hard time keeping up with the school work, it was the social part that was more awkward. I was the last to get my driver's license, last to start dating, all my friends were much older than me, especially when I was dating. And that also meant I went to college at 17....
It's just something to think about....it is much easier to be the older leader of the class, than the younger follower. Why not give her every advantage available to mature one more year. She will be at the top of her class, will have the extra advantage for all sports and athletics she tries out for, will be the first to drive and date, and will have the maturity to deal with peer pressure when it comes around. As far as academics, there are many gifted and talented programs at schools, so have her tested as soon as she enters Kindergarten.