Eloquence is not my strong point when I first wake up :P but yes exactly that.

I wouldn't though put a child in school over my career. I just couldn't. I guess for me I've seen that happen. And children are rarely kept down these days (once they are in the system) with a fight unless there is extreme social concerns so I have seen children struggle academically/socially/emotionally who should have stayed home. And the social problems only arise in the second half of primary school and is directly related to confidence academically. And by then even choosing to keep them down at that point has social ramifications. Emotional maturity as well as social maturity are so important to me because for a large part of primary school these kids can coast until thy reach the second half of primary and then their confidence starts to break. And this impacts hugely in secondary school. And then you have the concerns of how well a child can handle the stress of exams and study in the final years. I have high school teacher friends who often comment on the emotional maturity being extremely obvious in the last 2 years and how that impacts greatly on how well they do. So for me even though I have a younger child I wouldn't hesitate in holding them back if it were necessary because it would feel to me like a short term solution with long term effects.
Really it is one of the reasons why more should be done to reign in childcare costs - for most people with 2 or more children childcare costs are the biggest expense after their mortgage sometimes equaling it - and no amount of going vegetarian or penny pinching is going to come up with the money needed to pay for childcare (especially as it is likely to continue to rise as it always has and no change in the rebate). Alongside that doing more for part-time and flexible working.

Although I personally would just go with the 5 by 1st of Jan you can go system and remove any element of choice from the equation therefore keeping the overall gap between the oldest and youngest smaller in a year group - which if age is such a big deal I think is not a great thing. I think that is quite a fair system - and the basis of the Finnish system which everyone rates, is about it being equitable and accessible for all regardless of economic status.

The Raising Boys book I have read, and while some bits are interesting I think it makes a lot of generalizations, and those who love it are those who see those things in their own boys but not everything holds true for all - which is why you can only make the decision based on knowing the child, the family & the school. (Not all of school is about sitting still). At the moment both of my two fall into the 'no choice' camp but we may not always live in VIC, and if we lived in NSW both could go to school a year earlier if we chose, if we went back to the UK for a bit both DD would be a school now and DS would start a year and a bit earlier too - so I have thought a fair bit about what we would do. DD I know would be fine with the UK system and would be fine to start next year if allowed. DS is too early to tell but if I thought was ready I would have zero qualms (well in UK you don't get a choice) even if he was one of the youngest. I don't believe emotional maturity is set by your age or when you start school or that it is a linear progression throughout your school career. As far as I know there are no studies which show that younger children do worse in exams? I know there is some slight correlation between doing well in sports and being oldest in the year due to physical characteristics of being older but that is very minor.