Kindergarten Redshirt Year

All of my kids have summer birthdays and in Arizona meet the age cutoff (must be 5 by Sept 1 or else they have to wait until the following year to start) to start school right after they turn 5. However, by doing that they are young for their grade. Our daughter who has a July birthday started school in August after just having turned 5. She went to school with kids who were already 6 and kids who would turn 6 a few months in. She was the second youngest in the class with a little boy turning 6 a few days after she did. I didn't worry about sending her because she was more than ready both academically and socially. She thrived in school and had a wonderful year. I expect her 1st grade experience to be more of the same.

Our son just turned 4 at the very end of May. He is slated to start Kindergarten in August 2012, so next school year. I have recently been having discussions with my husband about "redshirting" him and waiting to start him until August 2013 instead, so he would start school having just turned 6. My reasons for doing this are many but primarily while I have no doubt he is likely ready academically I do worry about him socially in the sense that I feel schools are set up for how girls learn. They are not necessarily conducive to what is best for young boys. I don't know that he could sit still for 20 minutes and listen or work on an activity and I don't know if in a year from now, when he is able to start, he'll be ready then either. He's a well-behaved but highly active boy and I don't want him "beaten into submission" at school if giving him an extra year can harness and tame some of that energy naturally. There is a ton of research to back up that boys who wait a year and start a bit older tend to do better in school long-term. There is also the whole NFL Hockey thing where statistically NFL Hockey players tended to be older for their grade in elementary school. The theory goes that they are more physically developed than some of their peers, thereby becoming the better players in high school and college. There are also cons which we are well versed in too.

I've started mentioning my dilemma to a few friends only to find out that many of them are struggling with the same decision and for many of the same reasons I have mentioned. I go back and forth but I keep coming back to the fact that I have never once heard a parent say, "I wish I wouldn't have held my son back that year." However, I have heard many, my mother included, say, "I wish I would have held my son back and given him an extra year to mature a bit."

I am curious if you have any experience with this? Did you hold your son back? Do you wish you did? Were you intentionally held back?