Yes that one can be tough to explain, especially after the Dropbox "magic". Still it's a very valid use case that clearly highlights the tradeoff between "in the cloud, so always available, but at a monetary and potentially privacy price" and "not in the cloud, so as unrestricted free and secure as you make it, but needs a reachable peer".

It's not as fire-and-forget as Dropbox so I don't see everyone using AeroFS, but there are quite a bunch of non-techies that can get it and could be very interested in such features.