Yes, I think it did help aspects of my personal development a lot (and probably prompted my current career!). I've always liked teaching, and helping, and listening.
On the other hand, I never really had friends at school. I remained on the outskirts, in my helping role, and never really learned how an equal frienship would work. I listened to others' troubles, but wouldn't have been able to open up myself, as it was never an equal sort of relationship, particularly in the early years. I felt different, and very shy, and it was partly this experience of not having equal friends at an early age that contributed, I think. It wasn't a lack of social skills, but rather a lack of suitable opportunities for them. I didn't really want to play/talk/do what the others were doing, exactly, as I had different interests or did things at a different level. So I learned lots of useful things about empathy and getting along with them and helping others and fitting in where you don't share interests/abilities, which was indeed very useful, but I missed out on the sort of friendship skills and intimacy that you get from equal sort of peer relationships, and that hindered me later on in school. By that point, I didn't really know how to make and keep friends, because I had only ever experienced this 'older sibling' role.
I finally met people who shared my interests and love of learning when I went to university, but then I had to learn some of the basic friendship skills that I had missed, and it was very difficult. My self-consciousness and feeling of being different had increased ten-fold as a result of always feeling out of step at school.
I think I have never quite managed to fill in some of the missing gaps socially. However, I think I would have other, different gaps if I had skipped a year. So whilst I can see the flaws in my own experience, I can see that there would have been different problems if something else had been done.
One year, I was in Year 3, and got sent to the Year 6s for literacy, as they had it at the same time. My teacher was resentful about it, the year 6 teacher was resentful, I was embarrassed and ashamed because I knew it was causing problems for them, my peers were bitter that I got to do something different. The only people in the situation who weren't unhappy, in fact, were the Year 6s that I got to sit with and work with. They liked me, I liked them, we got on well together and that part of the experience was really worthwhile. Not sure how else it could have been done differently to make any of it any better, though. It is one of these things that has pros and cons to all options.