I like KBFS a lot, but you have to be careful about trying to use it as a Dropbox-alike. KBFS is always-online. If you have no network connectivity, you have no files.
They have been working on this and you can actually do it today even if it's not very well documented (again, haven't tried myself):
$ keybase fs sync --help
NAME:
keybase fs sync - Manages the per-folder syncing state
USAGE:
keybase fs sync <command> [arguments...]
COMMANDS:
enable syncs the given folder to local storage, for offline access
disable Stops syncing the given folder to local storage
show shows the sync configuration and status for the given folder, or all folders if none is specified
help, h Shows a list of commands or help for one command
If you don't mind getting your hands a little dirty, you can basically just rsync a given local folder with your `/keybase` folder on a cron every so often.
It's obviously not a right-for-everyone kind of solution, but it does get you fast local offline sync functionality with very little effort.
It's also not particularly fast.