Was able to answer my own question!
- EVENT: After updating an existing user account
- CONDITION:
- Data > List contains item - LIST: account-unchanged:roles, ITEM RoleA
- Data > List contains item - LIST: account:roles, ITEM RoleB
- ACTION: Show a message on the site=Role changed!!!
If you specifically want a message when a role was changed from one to the other, and not simply added, add another condition but NEGATE it. In my example, I would add:
- Data > List contains item - LIST: account-unchanged:roles, ITEM RoleB (Check NEGATE)
- Data > List contains item - LIST: account:roles, ITEM RoleA (Check NEGATE)
See https://groups.drupal.org/node/94379#comment-631148 for reference. I had been focusing on the VBO answer there and used this comment in conjunction with that approach and still had trouble. Just now thought to look at it on its own... and voila!
Hope this helps somebody!