Grey Council, I agree with your teacher - I wouldn't bother with Coroneos for the most part, as its theory is awful (explanations clear as mud, IMO) and there are plenty of good questions in Cambridge - in that sense Cambridge is a good replacement for Coroneos, but I don't think of it as just an updated version. Also, Coroneos can ask questions in obscure ways at times. However, Coroneos does have some difficult questions if you're looking for a challenge. Sorry if I didn't make myself clear - I wasn't trying to have a go at you. I guess I should try to avoid posting in the middle of the night when I'm tired!
As for Parabola and the benefitsd of competition practice and Maths group, etc., I really think this helps. It is especially useful in practicing looking for other approaches to questions - For example, consider conics. There is almost always the 2 - 3 page obvious way of doing the problem, but recognising the half page way can let you pick up alot of time!
As for SGS / SBHS soccer / rugby matches, I was never much of a sportsman at school, so I went to very few games. However, when I was at school, I do remember that we routinely lost at most sports! (I don't know whether you saw it, but a couple of years ago there was a list published in the SMH of the league table of rugby for the GPS schools, and the HSC results league table. With one exception, the list was reversed!)