This main thing you'll need to worry about... it having all of your iPhone's data sync'd somewhere. When you, eventually, update to iOS 6 you're going to have two options. Update & restore from a backup... or restore it as a New Device. Restoring from an older iOS version's backup that was Jailbroken at the time will cause many unforseen issues w/ your new iOS. So, be sure to have your contacts sync'd to an email account, etc.