personal_options_update hook and update failures

I use the personal_options_update hook in a plugin to alert me when a user changes their profile.

Problem is, the hook is called before the update succeeds, and I have no way of knowing if the update might fail for, say, an email address which is already in use.

So I put some logic in my class’s _destruct() to check if the relevant fields really have been updated – and that seems to work. But I discover that I can’t really depend upon any WordPress service during the _destruct(), because WordPress is already winding down.

I can’t find any other hook which will be called when a profile update has succeeded (or failed, for that matter).

Does anyone have a solution?