Similar to post edit history, I would like to suggest history for custom fields. In XF2 all profile fields are custom fields. Threads will have custom fields as well.
There are various benefits for this:
prevent data loss and destruction in case anything goes wrong
easier to revert fields...
I'd like to offer a suggestion on member profiles.
When a user creates a status update and it is edited for whatever reason, there are no logs under tools > moderator logs.
The same applies to any replies to that status - if edited too. There are no logs.
Also there is no history...