This size issue sounds familiar. My DH (6'1'', Sept. b-day) said he didn't grow until after high school, so it wouldn't have mattered if he started a year later.
My DS7 was short even before his grade skip. When he went to visit the HG school he attends now, the GC told the class he was a student thinking about coming to join their class. One kid said, "He's in 2nd? He looks like a first-grader!" The GC matter of factly told them that DS skipped first. There were impressed "ooh's". The day he started, there were a couple kids who were interested in his age - the girl who was the tallest in the class, and the kid who used to be the youngest.
That was the last we heard of any age talk, but DS says he's glad that his birthday happened before he switched schools, because he's a little embarrassed to be younger and wouldn't be able to avoid talking about it on his birthday.
