Yes that is correct. What is interesting is when SkyDrive was in it's early days, when it was Windows Live Mesh, had sync over LAN. However, it was removed. I believe the idea (of I remember correctly), was that if you sync over LAN, well you have the file on the cloud. Making you, unable to access the latest version or the file at all, if you go somewhere else, and access SkyDrive on the web or install the program on another computer, outside of your home.
I use a private(no tracker) torrent to move big files between 2 PCs ...its the most efficient method by far.
I've never used 'bittorrent sync' so I'm not sure, but after a quick scan of their faqs, I can see they use a tracker + you have to download an app rather than just using a generic torrent client + there is some kind of encryption involved ..so I'm guessing its not quite the same or as efficient as my suggestion.
Im not that up to speed on torrents, but I suppose this is a one way sync whereas BT Sync is a two way sync.
^^my suggestion is a 'two way sync' also ...call me old fashioned, but I've never really considered this type of file sharing as a 'sync', more just passing large files, back & forth, between 2 PCs ...or peer-2-peer, if had to put a label on the transaction.
