escrow is the best option, and distributions of vesting 1 - 3 months, like the bounty managed by bubbalex. because what I know, the Bounty Hunter after receiving the coins/tokens will definitely be dumped. but BM, escrow, that's all no guarantee, the main point here is the project, I think a successful project will keep its promise to hunters. It is useless to receive tokens/coins but they are of no value.