Can't answer your question Thorns, but I have been playing a place only sytem for quite a few years now, using bets tote (Metro races only) it shows a tiny but regular profit, a few years back I tried to increase stakes from $100 in stages trying to get , well I don't really know but definitely in excesss of $500 bets, over time the profit grew slimmer and slimmer until it disappeared.

I reverted back to $100 bets and it certainly did re-appear. So somehow it finds it's way into the pools, ( remeber I am backing with a bookie, albeit Corporate) and it really only took a few bets of $200-$300 to affect the Divies.