In addition, enterprises are likely to have more leverage with cloud storage providers than with companies that sold them storage infrastructure, Wettemann said. If there's a problem, a service provider will have more incentive to make the customer happy because it needs the next month's subscription fee, she said.

If push really comes to shove, a cloud storage provider might hold a customer's data hostage. At Rackspace, it's never come to that, Engates said. Nirvanix includes language in its contracts that lets it block a customer's access to data, but the company would do everything in its power to resolve a dispute before it came to that, Zierick said.

IDC's Woo thinks serious conflicts between a cloud storage provider and a customer are unlikely because the service is so simple.

"The most optimal relationship to have in a backup scenario ... is a non-existing one," Woo said.