Speaking with many friends in the last few years who are red-shirting their 5yo in order to make them the oldest in the class to bring such advantages as more confidence, larger size for sports, feelings of academic superiority and hence better performance, etc. and they are all spouting this "data" out of the book Outliers. (I haven't read it yet.)

What do parents of gifted children think of this seemingly popular culture of red-shirting K? Does being that much younger (especially if skipped) hamper you children's emotional/psychological well being, and make them any less likely to stand up for themselves, or be leaders? Is there any of this effect on home-schoolers who are accelerated, but probably don't really realize how much because they have a lot less contact with what average grade-age peers are doing?