Hermes - have you tried/perfected Quinella betting? In my opinion (again feel free to ignore it) trifecta betting is very risky for two main reasons:
1. It has the biggest TAB take figure (20% for Supertab) of any of the bet types so you have an extra disadvantage you have to overcome.
2. None of the TAB's provide approximates before jump on trifecta combos so you can't see if there is any value in the bet - you often get huge variations in the payouts between the TABS (not unusual to see one TAB pay double what another one pays). Would you place a win bet not knowing if your selection was paying $2 or $10???

I see these items as huge disadvantages to successful punting and that is why I would generally go for Quinella before Trifecta (the NSW tab at least gives approximates on Quinellas - not sure about the other TABs).

Again this is just my opinion and I realise that some people do come out ahead on Trifecta betting - just seems like a higher risk than Quinellas to me.