This site runs on Backdrop CMS. I have changed from Drupal because I have found that it is becoming increasingly more difficult to syncronise the Configuration and Content between the Local, Dev and Production sites in Drupal 8. I think that Drupal has moved away from being suitable for Non-Profits towards Enterprise use. Fortunately Backdrop is based on Drupal 7 and has been set up for Non-Profits to be able to use with relative ease.
I have been using Drupal since 2012 from version 6 to 8 and am beginning to get an idea of how it works. I am now an Individual Member of the Drupal Association.