How are your skills? The ZyXEL NSA310 is unbeatable in price/performance, and with a little effort you can install Bittorrent Sync
Do you know what, it was one that in my sights. It I were to install these for me personally then yeah, no problem (although having said that, I would probably build a FreeNAS or similar home-brew system). This is actually for a colleague and whilst I don't mind setting it up, I don't really want to provide on-going support - if you know what I mean. However, I will look at this device a bit harder and see if it will fit the bill.
I take it that the Bitttorrent sync means that you can set up a Bittorrent server on both NAS unit, then sync between them - rather that to a cloud based Bittorrent service?
PS - thanks for getting rid of the spam