Why not simply use PASS with your Keybase gpg key?
I also wanted to take advantage of KBFS to do the encryption transparently and expose records as individual files. KBSecret just provides a structure; you can use plain old shell scripts (and I/O primitives) to access your records once they're in place.
It's more of an experiment than anything else currently, but those are the two big motivating ideas.
They've also open-sourced KBFS itself and the `keybase` client [2][3], but again, not sure on the audit.
[1]: https://keybase.io/docs/crypto/overview