We did this 3 years ago, doing K twice - thinking along the same lines you've outlined (and more - we convinced ourselves on many levels that it was the right choice...).

We really regretted the decision after the fact.  Our kid was then one of the oldest in the class, rather than the youngest, and ended up bored academically after being held back - which created a whole new set of problems. And once we held them back and realized it was a mistake, we couldn't get them moved back into the 'right' grade. We ended up transferring to a private school just to get our child back into the 1st grade (now finishing 3rd grade, still in private school).

While at the end of the day, its what you think is best for your child, of course - there are definetely cons as well as pros. When we made the decision to hold back, all I heard (or maybe wanted to hear!) were the pros.

Thank you very much for your responses. Here's the answers to the expert's questions:

My son looks slightly younger that most of his classmates (8mo. older than him) and clearly younger that the oldest ones (1yr +). He is quiet, well behaved (teacher's assessment) and and gets embarrassed easily, also doesn't ask questions if he's confused about something. Tattletales sometimes and gets easily distracted by what others are doing. All year he has seen himself as being the shortest, youngest and slowest to learn how to read (even though he is not the slowest reader). He now pretends to read chapter books, even brings them to school. According to him he can read 122 pages in 1 hour!

He has a 9yr old brother and 2yr old sister, he is very gentle and caring with the sister and cannot easily agree on games to play with his brother. Outside home he prefers to play with girls or younger kids. Only wants to play with boys his age or older if it involves sports. The teacher thinks that he is and acts younger that the class. Academically thinks that with extra school support and tutoring during the summer he can stay at "grade level". She describes him as a "quiet observer". No testing that I'm aware of has been done or suggested for him.

Next year his teacher will be "looping" to 2nd grade with the entire class. My son has repeatedly told me that he doesn't want to loop because the classroom gives him a headache, even though I've explained that he will not be with his friends and teacher (he likes her). The headache is a complaint that I have heard all year round. It only happens in the classroom. Not at home, gym or art. His pediatrician says there's nothing physically wrong but did ask me to consider retention for him. She though that being the youngest will be socially challenging for him during the teenage years.

The teacher was concerned that he might be bored next year but thought that he could be given extra work. I have asked my son if he would like to be one of the oldest in the class instead of the youngest but he would like to move to second grade next year. Also consider that he has always looked up to his older brother, even wanting his same teachers or reading the same books that he really has not interest in. Retaining him will put him behind his brother another year. However, this week he has come home telling us for the third day in a row how they just celebrated somebody Else's 8th birthday in the classroom, summer birthdays I guess. Remember, he won't be 7 until October!! That bothers ME.

One more thing...There are 2 boys in the neighborhood who are first graders and one who is a second grader being held back from 3rd into 2nd grade next year. That means that all 3 neighborhood boys will be 2nd graders next year. Something to consider?