I think oversensitivities confound the question. (imagine a 1 to 10 emotional scale)... being equally emotionally mature could mean that kids at age 8 can control emotions at level say 5 or below. But when a kid is oversensitive, then they may experience a thing that is a 4 for an average kid as a 7 and not be able to control it.
To compound the confound, younger gifted kids may have more keenly tuned senses of justice and fairness earlier than other kids. So the average five year old kid sees nothing amiss when their friend of two minutes wanders off to play with another kid, but the gifted kid may see this as a deep and grave social injustice and have a huge emotional outburst.
Guess I'll find out today how this plays out for DS as it is first day of his skip.
