I have (I believe) updated the SQL correctly to v1.5.0 compatibility, and tried an install on a fresh v1.5.0 on my local server. The SQL patch went smoothly, and all of the entries show up in the database as they should, in admin_pages, configuration and configuration_groups tables. The db fields look consistent with other adjacent fields. However, the Editable Centerboxes item never shows up in the Configuration dropdown or in the altnav, even after logging out and back in. Guess I'll scan the thread for info on this, unless someone can offer suggestions quicker than that:)

The define pages show in Define Pages Editor as they should. The existence of the base define_middlebox_x.php file is necessary to the display of the /your_template/define_middlebox_x.php, but none of the other define page files are needed with the exception of one /includes/extra_datafiles/middlebox_filenames.php with all nine pages' info.