The biggest problem I have with centralized servers in the first place is that I don't trust my data with them. If it was decentralized and open source, that's an app I could see myself using.
I think that AeroFS only uses central servers to identify the IP addresses of participating hosts and negotiate a connection. AFAIK, the actual data flows directly peer to peer. So, even a malicious employee or government snoop would only know the IP of swarm participants. Presumably you'd still need to intercept and crack any encryption between nodes.
I suppose.... but I'd be interested to hear their plans for when it's not a private beta. I would also be interested if the source code is visible to users (which is not the same thing as open source) . This transparency helps users know how safe their data is.
Closed source = no good for privacy.