The used WebDAV implemention shows wrong available capacity and has a limitation in the file size. The developers are aware of these problems and working on a better solution.
Cannot automatically back up photos on mobile devices replacing the need for Google drive or iOS fully. User then has to go and either manually select photos for upload or use cloud service and then encrypt defeating the purpose on mobile clients.
The configuration for EncFS is in the form of a dotfile (.encfs6.xml) and it's stored in the working directory. This way you only have to remember the passphrase because all the other metadata is stored in the configuration file.
From some audits in the past, EncFS has had some issues with being up-to-date as far as cryptography practices go. For example, it uses the same key for encryption and authentication or file holes not being authenticated.