If you're averaging A, that's great! but it also depends on a few things.
1) How well your cohort are performing in these subjects. ie. you're averaging B+ in EL and the majority of the cohort are averaging A+, that would bring you down.
2) How well you perform in your exam.
3) Appropriate scaling per subject.
SAC marks aren't everything, but it is always good to keep a consistently high average in all SACs throughout the year, because that is usually an indication of your skill and how well you will go on the end of year exam.
I myself am going through VCE Year 12 this year and I'm averaging an A in all my subjects and I got 36 and 33 as study scores last year for Music Performance and IT: Apps. Those two mid thirties may aid me if I flunk in a subject this year. See them as extra increments towards your overall score.
If you keep up the good work in your subjects and aim for high scores all year you should be fine. I'm quite ignorant when it comes to scaling, and that may affect your overall score slighty or even dramatically, but if you perform consistantly well, then you should come out on top, especially if you perform exceptionally well in Methods and English Language.
Hope that helps!