I understand that there is some confusion from some users about exactly what the delete function in this plugin does. Here are the messages you see, if you can suggest ways to make them even more obvious then I'll definitely consider changing the text:
PLEASE NOTE: deleting the data created by this plugin will delete EVERYTHING (pages, posts, comments, users - everything) on your site, so DO NOT use on a production site, or one where you want to save the data.
When deleting (non-BuddyPress):
Delete all user and blog data in your database.
WARNING: This will delete ALL data.
When deleting (with BuddyPress installed):
Delete all user and blog data in your database except for information and tables for blog ID 1 and user ID 1. This will also delete all Buddypress groups and friend relationships.
WARNING: This will delete ALL data, making your site as it was when you first installed WordPress and BuddyPress. This will also delete all Buddypress groups and friend relationships.
Just above the delete button (in bold red text):
THIS WILL DELETE ALL YOUR DATA. ARE YOU SURE YOU WANT TO PROCEED?
If you can suggest how I can make these warnings any clearer I'll definitely consider changing the text.