I first started blogging using a wiki and, after two or three years, switched to Drupal. Since then, Drupal has gone through several major version changes, each requiring a more or less painful transition. I had been holding off waiting to see if I should switch from Drupal 6 straight to Drupal 8. Eventually, I decided that D8 isn't ready for me to use. And I migrated to Drupal 7.
It took a few tries to get this far. I was able to get the content (mostly), although I discovered that the migration tool had renumbered all of my nodes, which is what I had been using for "permalinks". It seemed stupid to lose all my permalinks, so I spent another 5 hours or so figuring how out to make that work. In the process, at one point, I accidentally trashed the database of my Drupal 6 system, so it required another hour to reconstruct the site from backups. But eventually, I have a new site, with a responsive theme, with most of my previous data. There are still some things left to sort out, but whatever: it's enough for moving forward with, so I've switched the new site to be my live site. Yay.