1. the "Default Style"
2. TBAC1 (the production one) - set as default
3. - child of TBAC1, for testing only
#1 and #3 have "Allow user selection" unchecked.
From the Admin control panel, if I use Test Permissions on a normal user (ie, a dummy user "John Smith"), the style chooser shows up at the bottom of the page and I can pick any of the 3 styles #1, #2, or #3.
If I log completely out and log in as the test user John Smith, the style chooser link is gone from the bottom of the page and I'm (correctly) stuck on style #2.