I also use some PPM systems, namely Green Light, Solitaire, Shadow and Target. It is still early days but shadow is making a good profit while the others are struggling. Solitaire gives a reasonable profit if you bet for a place.
Another system I have used with success(once again still early days) is choosing races with 9 to 14 runners where the favourite is paying $3.00 or more. With 2 minutes to go you check which horses are 2nd, 3rd and 4th favs. If their prices are averaging $6 or more you place a win bet on each in proportion to their price i.e. the higher the price the less you put on and vice versa. This means all will return approx the same amount if one of them wins.At the moment I run at 65% win rate with each win returning about 100% profit. I have made up a simple works spreadsheet that calculates how much I put on each horse.It takes about 1 minute to do the calculations and place the bet. Anyone with even limited knowledge could make up the spreadsheet.This is still only in the early days but I'm hoping, because very little else works.