My application has auto-saving and versioning/revisioning (keeps a copy of every change).
It also has the ability to save draft versions of things, which I define as "something that you want to save but isn't valid". By valid I mean, normally say a First Name is required, but this object doesn't have one, but you want to save it anyway (like a Gmail draft).
The question is, is there a benefit to the user of keeping all the draft versions in addition to the regular (valid) versions?
The drawback would be that, in their list of revisions they can go back to, all the draft ones would be there too. Do they want to rollback to a draft version?