I wonder how an insurance agency could possibly be instantiated on such a platform, or if that is something better left to other realms. It looks like arbiters are serving a very direct escrow and insurance role in this scheme, but I think another good input to this might be a betting market wherein the future reputation, price, or profitability of the arbiter himself relative to others may be a subject of speculation and bets may be made on this account. This way you may hedge your bet on an unproven arbiter by placing a small bet against your own judgement, and you can also use the price of these bets as a more accurate and precise measure of the consensus on reputation.