User Fields and User Management

We've noticed that:

• If you remove a user from a project then that user is removed from any User Fields (Author, Creator, Detected By, etc...)
• Deactivating a user does not conceal them from Project Membership (though it does stop them from being visible in the Drop Down lists)
• Project Membership does not have any Filters

We have long running projects (10+ years with releases every month in some cases) with literally hundreds of active users, including many contractors and interns.

We are transitioning these projects to Spira and we don't want to lose important information (like Detected By) when a user leaves us by removing them from the project. But at the same time we don't want project admins to have to manage user lists cluttered with an ever growing subset of deactivated users.

Do you have any suggestions?

Thanks in advance,
Will