Reputation systems have demonstrated their interest in stimulating cooperation in peer-to-peer (P2P) systems. Their key operation relies on collecting, processing, and disseminating the feedback about some peers’ past behavior in order to boost their cooperation, albeit this is susceptible to collusion and bashing. Additionally, estimating reputation generally relies on a partial assessment of the behavior of peers only, which might delay the detection of selfish peers. This situation is rendered even worse in self-organized storage applications, since storage is not an instantaneous operation and data are vulnerable throughout their entire storage lifetime. This paper compares reputation to an audit-based approach where peer observations are carried out through the periodic verification of a proof of data possession, and shows how the latter approach better addresses the aforementioned issues of inciting cooperation in P2P storage.