OVER9000, having done Specialist Maths this year I can say personally it was a really interesting subject. If you are decent at maths, and if you enjoy a bit of maths from time to time, doing Specialist Maths can be really rewarding. After doing Specialist, you will also realise that Methods also becomes extremely easy. Specialist covers most of the Methods course, with mainly just the topic of probability which stands out alone for Methods. Considering you are averaging 80%, I think that is more than enough to continue with Specialist.
Comparing Specialist with General Maths in Year 11 I can say that some of the year 11 material is irrelevant, however, a lot of the theory learned in Year 11 is relearned in Year 12 and applied to more complex and difficult analysis problems. Year 11 General Maths is kind of like the grounding knowledge you will need to take on Specialist Maths. The topics which will be covered again are trigonometry, calculus, complex numbers, vectors and dynamics, but at a more complex level. This theory is re-taught in Year 12, however this time you will actually apply these concepts to questions, often utilising many of the 'ideas' you have come to learn to answer an analysis question or short answer questions in the final exams.
As kdgamz has said, Specialist is largely a 'concept' subject. You must understand the concept behind the maths to do well in it. Although doing 100 trial exam papers may help you understand how to do specific questions (which will help you for Exam One), if you do not understand the particular concepts, you will struggle to work through harder and more unique VCAA analysis questions in Exam Two. Overall though, I would say if you work consistently through the year, by the end of the year you will come to enjoy doing Specialist Maths rather than fear it.
Just my two cents
