My DS has a lot of the traits that cym describes in her son. So far, though, we have not had a problem with him getting overwhelmed. I don't know why we have escaped it or if it will turn out to be a problem later. I do think he is pretty good at setting limits. I know one thing that seems to have helped--his preschool teachers.
When DS was in preschool, he tried to take on on many adult roles in the class--monitoring rules, helping other kids, etc. And the teachers did not let him get away with it and they told us not to either. They told us he only had a few years to be a kid and he should enjoy it. They would tell him, "You are a kid. Your job is to play and learn and have fun. Our job is to enforce the rules. Eventually, you will be a grown up and then you will be in charge of the rules, but not now!" When we saw him doing something too adult at school even years later, all we had to say was, "What is your job?" and he would say, "Oh, yeah, I'm the kid." It really seemed to help a lot.
I don't know if this approach will help at this late date. But I think it has helped prevent DS from becoming too responsible for others.
