You should be able to rejoin the mainstream when there is a full update.
How can you sign up for the beta program without signing up on the device?
The shop.boox.com Support/Download section is a desert of old manuals.
If anybody has the beta links for the Go6 v4 it would be appreciated. Or if you are signed up for beta on the Go6 and you want you can PM me your device MAC and I'll fetch the links myself. I won't use the MAC for anything after grabbing the links. Currently there are no mainstream updates for the Go6.