As I previously mentioned, I'd got a basic migration of configuration and content from the Drupal 6 Gallery Guide to a new Drupal 8 site up and running fairly quickly. It's clear that a lot of good work has been done on the various migrate modules.
The corollary of constant change is ignorance. ... we computer experts barely know what we are doing.
We function well in a sea of unknowns. Our experience has prepared us to deal with confusion. A programmer who denies this is probably lying, or else is densely unaware of himself.