This makes sense. I can't think of any obvious big downside. Two minor issues come to mind:
- It might make curation slower, but who wants to stay glued to a screen anyway?
- You will have an incentive to wait for 12h and see which posts yield rewards before adding your vote. Then some posts might emerge as gold-pots and others will be left in the dust. That would equal the current bandwagon effect. Personally I would just vote there and then, but there is a possibility to game and skew the system.