Plus, pre-2.0 shares had a killer feature: read-only encrypted peers. These were peers that would only retrieve the encrypted data in read-only form.

Using read-only encrypted peers, you can have an always-on node in the cloud, with the security of end-to-end (client-side) encryption.

I hope they will bring this back in Sync 2, but it seems much harder now that they switched to the identity model.