Some will let you export the data, but it's a hassle. They burn it to a DVD and ship it to you and you have to sign tons of stuff freeing them of any liability.

Some will let you export the data, but it's a hassle. They burn it to a DVD and ship it to you and you have to sign tons of stuff freeing them of any liability. Otherwise you just ask customers to re-authenticate. Often you have a few months headway for a switch like that.