Stuff like this in release notes gave me pause:
"If you have a Family Pack master account, you will lose the ability to create or delete family member accounts once you move to iCloud. You should complete any family member account management prior to moving.
Some contacts, as well as mailing addresses within some contacts, may be duplicated after moving to iCloud. "
I'm reading that some data will be available to devs after the beta ends. Perhaps they will be keeping...