Stephen -- I'm not sure why you think of Favorites as being a backup or disaster recovery scenario and somehow different from any other file sync that OneDrive handles. It's just another folder full of files, after all...
We have a significant number of users who use at least 2 different shared workstations in the course of an average workday, sometimes more. When they add something to their favorites on one computer, they expect it to be available on the next computer that they log onto. It's not a case of disaster recovery or replacing a computer, this is their every day workflow. For more than a decade, we've used roaming profiles to accomplish this, but as you know roaming profiles can be a bit painful to deal with sometimes. We've wanted to move away from roaming profiles, but for a long time U-EV was part of MDOP, which wasn't available to us. More recently, the info coming out of MS has made it seem that cloud services will be the preferred way to synchronize user files and settings. I've even heard rumors in the past months that UE-V is not going to get further development and may be deprecated in the not so distant future. I am not interested in putting in the time required to learn about and implement a feature which doesn't have a future at this point.
Please consider adding support for migrating/syncing the Favorites folder along with Documents and Pictures. It should be fairly easy to do, and would certainly have a big impact for users.