NO offense, really, but I held my oldest, and will hold the other three as well (they are all within days, to a few weeks of the cutoff).
As far as me holding my child back, and it affecting your child, really I don't care. I am doing what is BEST FOR MY CHILD, not what is best for your child. We put a lot of thought, time, and research into our decesion, and are 100% happy with it.
My oldest started Kindergarten this year, she was 6 right after it started, she is NOT the oldest at all. In my district kindergarteners are pushed very hard during the day academically. Kindergarten is not the same as it was when I went many years ago, most days my kid does not even get play time, they have been outside once (they are also half days), and gym once a week, so, there is lots of work time. She did go into kindergarten reading, but has not been bored once, I work with her at home to challenge her.
You need to sit and really talk with teachers, (everyone we talked to in our district recommened holding a year), look at the curriculum, is it full or half day, ask the school district if most people hold or send their kids, and most of all go with your gut.
I firmly believe giving my child an extra year to be a CHILD, to play, and have very little commitments, will never hurt her. Kids grow up way to fast as it is, and I know we did what was best for my child.
Good luck, it is a hard decesion, but if you do your research, and listen to your heat, you will find what is best for you and your child.