I agree with Neil that this is the correct way to use ratings (betting those with a better price than the assessed rated price)BUT (and I have no knowledge of the PROPUN rating service ) with a couple of well known and respected rating services I found a long time between collects as the majority were well under their assessed odds and those that were not were up around the $30 mark which doesnt give you much confidence if price is related to chance.
In the end after fruitless days of not being able to confidently put a bet on (either too low a price or $30 - $40 jobs I looked for a better way)
Cheers.
darky.