Timebanking is a service-based community currency, built on the principle that everyone's time is valued equally. It has potential for community building and reenergizing neighborhoods, but it faces several adoption challenges. We report on the largest investigation of timebanking practices to date by analyzing a combination of service exchange records from the three largest hOurworld timebanks with over 3,500 members with 33,000 completed service exchanges, and a survey of 446 members of over 120 hOurworld timebanks. Our findings suggest that the ideal of 'equal time, equal value' that is at the foundation of timebanking is a source of tension between members with instrumental versus idealistic and altruistic motivations. We suggest that future peer-to-peer systems must incorporate different rewards and incentives in order to accommodate users with different motivations.