In addition to the comment below about CrashPlan requiring you to use their client software, which limits abusabiliy -- I am also seeing signs of strain from CrashPlan. They have always had a policy that claimed they would delete data from machines that hadn't touched the service in a long time, but they had never implemented this in practice before; just last year they finally started sending out threatening letters to people saying they're going to delete data on short notice. (And they didn't really back down when people got angry.) This tells me the storage expense is starting to hurt them.