As a casual user who has occasionally used Keybase for sharing work-related sensitive things, it will be interesting to see how KBFS vs. upspin plays out. As far as E2E encrypted file storage goes, the two seem to offer very similar abilities. Obviously, Keybase's other services offer more in the way of messaging and user social proof. I also like the way you can privately share things with individuals using the directory names, vs. the ACL file in upspin, though I guess that allows read-only sharing and a stronger concept of ownership... you can't do that for shared private files in KBFS right?

The other cool thing about upspin is the ability for anyone to spin up their own server infrastructure for storage. I can imagine a service offering an on-premise secure Dropbox to paranoid big companies. I'm not sure if you can deploy a private Keybase, though their client code at least is open source.