My local TAB used to have Read's Ratings and I tested the top 3 system over a short period of time. It did not fare too well mainly because the divvies were unstable. Quite often the 3 horses were under the total percentage one minute prior to the race-start and therefore became a bet, but the final divvies showed that in reality it should have been a no-bet, and vice-versa.

But I did have some success betting only those that were "overs" even if it meant betting on only one horse in a particular race. I had even better success betting "overs" as stand-outs in exactas especially with races that had 11 starters or more.