I have tested 4 months again (same 4 months) using betfair prices for laying.

Unfortunately it showed a loss just over 10% after commission. The increased prices on betfair always make it hard. For instance there was 1 winner at $810 on betfair which was under $100 on tatts.

I tested this using both methods of laying (straight $1 or to lose $100). Both laying staking methods showed a similar loss.

As a guide if your using tote odds for testing then you need to be under 50% returned if your method uses odds any higher then $20. I also tested your system under $20 but it showed an even larger loss but the odds range over $20 also showed a loss by itself.

I couldn't find a way to make it profitable.