Many people are contemplating early kindergarten entrance for their gifted and/or late-birthday children. Conventional wisdom seems to be that leaving these kids back a year has no down-side. "Give them another year to just be a kid!" they say. "Boys mature socially/emotionally more slowly than girls, anyway. If he can't sit still, they'll give him Ritalin!" "He'll be bigger and stronger than all the other children, so they'll look up to him!"
Klaus has an early October birthday, so missed the kindergarten cutoff by a couple weeks. We decided to leave him back a year for all of the above reasons, plus the fact that he was in a good preschool situation that would grow with him. But there is a downside to red-shirting kindergarteners.
Size does matter. Yes, your son will be bigger and stronger than all the other children. Remember those older, bigger kids when you were in school? Were they the smart ones? Or the ones called "Moose" who may have been left back a year? Being older and bigger isn't a ticket to popularity. For gifted kids who may already have trouble relating to their agemates, being physically as well as intellectually different only compounds the socialization issue.