I don't think this would be terribly difficult to implement, considering that the necessary function is already (mostly) in place. Since what we have is grayed-out, and things we partially own and do not own are not, it ought to be pretty easy to do a sort based on our individual libraries. One click, and a "New to You" list is generated for any base package we choose. Database management isn't my forte, but I don't think this would be hard to bring to pass.
