Since we can choose to share or not share libraries from individual servers, I think it would make a lot of sense to allow us to turn the Allow Sync feature on/off for users for each server instead of as a global user setting. This way we can allow users to sync from one server but not another.
Kind of shocked that no one else is interested in this. I guess that speaks to how few people are using Sync and or multiple Plex servers. Shame.