Hi Hhbella,
Sorry to come into the conversation late, but thought I would share my experience of being a student at a NSW selective high school.
Personally, it was an enormously positive experience. Selective high schools were quite new and experimental when I was accepted in the early 90's (some time ago now!) Yes, there were expectations, some degree of competitiveness and a workload attached, but they were so worthwhile. In terms of expectation and competition, is was an opt-in situation...there was a culture of doing your own best, rather than being pushed by an external force (teachers, parents). The competition I experienced was more of a friendly rivalry, rather than a cut-throat rush to the top.

For me however, by far the best aspect was the social one. The vast majority of classmates were similar to myself in some ways (whether you want to use the label of gifted, geeky, nerdy, whatever) and so we had a really strong community where it was ok to be yourself. There was no pretending to be something you weren't, or trying to hide your talents, to try to fit in. High school can be a scarring experience for those that may seem a bit 'different' (my sister experienced this in the local high school), and many sadly spend their early 20's recovering from this. But, when you build a community of people who don't undermine one another (as can be the case in local high schools), magic can happen. High school is where many lifelong connections are made- for me, I met my husband there, and have a circle of lifelong friends with lots of interesting careers (including scientists like my hubby and self, an archaeologist, human rights academic, pilot, social worker, engineer, business leader).

Another thing to keep in mind- entry into a selective high school isn't a one-way ticket. There were many who decided after a year or so that it wasn't for them and transitioned back to local or private schools (this was my plan B when I started out too).

Of course, I am sure lots has changed in selective schools since the 90's. However I think that same social aspect that I found invaluable would still apply.

Cheers,
kathaust.