Can I tell if a contact has used their checksum to view/change their info?
We set up a group specifically to track who has completed the profile and use the profile setting option to auto-add them to this group. 

This way we have a group of everyone who completed the profile that we can exclude from future mailings prompting them to complete again. 

This obviously won't track if someone has just visited the page, but for us, we're only interested in submissions.