I support allowing PM bets to lessen strategic bets and increase "real" bets. Any publicly posted bets shouldn't be allowed to be changed or reversed secretly via PM, though. That would allow for manipulation.
Homer: [looking at watch] Two hours? Why'd they build this ghost town so far away?
Lisa: Because they discovered gold over there!
Homer: It's because they're stupid, that's why. That's why everybody does everything.