I have an idea for a feature request for sync that only makes sense. When syncing by default, you see all devices you are allowed access to. This means when user A goes to sync media, he is prompted to sync to devices that may be user A's , B's, C's, and D's. Of course you can limit their device access, but this requires a lot of work when new devices are added all the time.
An elegant solution to this might be to add another metadata tag to devices to hold users that have connected to them before. Then when going to sync content, only showing devices you have logged into before by default, and having an option to show all devices you have permission to sync to.