Nothing wrong with it as long as you don't fall foul of prejudiced, hostile people who decide there's something the matter with you and therefore refuse to take you seriously when you need their co-operation. It's a shame it's so hard to effectively lie about one's age - that might help to fix it.
I was always impressed that the Steiner schools have this attitude that kids shouldn't be pushed into learning this or that until they're ready. But a lot of the parents tend to panic when the school seems to be letting their kid "fall behind."
After a year or two at my secondary school, they decided that the lowest-performing half of our year would be "kept down," i.e. taught work that was a year behind the stuff the taught the higher flyers. I was part of the kept-down group. One teacher asked us how we felt about it, and most of us said we didn't like it. He said that we didn't realise what a good thing it was. I think he was right. It made things easier for us, and the only difference it made in the long term was that we had to stay at school for an extra year, and that we were a year older when we got to leave. It was one of those prestige schools that prided itself on getting the kids through their final exams quicker than ordinary schools could, but they'd recently started to be a bit more realistic because they'd recently started taking in working-class kids like me for the first time, and we didn't have the family support or money that the little toffs had, so we were a bit slower. It's hard when your dad can't help you with your homework because he doesn't understand it.
I think society (or maybe it's just the ruling elite) has too much of a sense of urgency for progress. Everybody's expected to push themselves to the max all the time. Imagine the reaction if you went for a job interview with a gap in your CV for the previous year, and when they asked you what you'd been doing, you answered "Nothing much, I just felt like having a break from the rat race for a while." Wrong answer, but it shouldn't be.