Tam-Lin

No, I'm saying that, at least on the NASes I have, you can install a single instance of BT Sync, and that install runs as user root. So it can access all files on the system, but if you write a file on a remote system, it will then be synced to the NAS and written as user root, meaning that, unless you make the NAS world readable and writable, no one will be able to write to the file. So right now, BT Sync works well enough if you want to use a single NAS as a file distribution system, but as soon as you want to put files onto the NAS from a remote system, you're likely to have problems. And again, I strongly suspect you'd be opening yourself to all sorts of file locking/coherency issues. It's not clear to me what happens if two users update a file at the same time, for example.

Right now, I don't think BitTorrent sync is a good fit for what you want to, although without knowing more about what you're trying to do, it's hard to know. It doesn't support multiple userids, so all changes are made and owned by a single user. And I suspect you'd have serious file locking/synchronization issues. What sort of files would you be sharing, and what are the use cases?

I have a synology NAS, and I was excited once an officially supported version of Bittorrent Sync was available. I was about to pay for a subscription, as well, until I tried it, and discovered that there's no support for using it in a multi-user environment. I'd like, for example, to keep my pictures in sync between multiple devices, but I can't because any new files are created as userid root, meaning I then later can't access them another way, such as in an SMB share. I'm still willing to pay, but only if I have some sort of confirmation that this will be fixed soon. Otherwise, I may be able to use the NAS as a read-only server, but it won't really serve my needs for syncing.