Rami's gone; won't reply.
I guess I'm overdue for an update of my E6440 guide. Outside sheer laziness, one of the reasons for not doing it was that I used a hybrid method to install High Sierra and retained that hybrid method for updates. By hybrid, I mean that, since Enoch did not support High Sierra installation and/or updates, I use Clover for initial installation and all subsequent updates. But for regular use, I still boot and run High Sierra with Enoch.