Can "Change Hosting" button be safely used to move website from Legacy Apache webspace to NG Hosting webspace? Does it preserve web hosting settings? Does the provider need to perform additional steps?
The behavior of this button is described in section:
When this button is used to switch web hosting type (Legacy > NG, or NG > Legacy), after switching website to new hosting type, it will be created on new webspace from scratch and will have default skeleton content. FTP will be reset as well. This feature is about website recreation on new webspace, rather than migration.
To migrate the webspace along with content, ftp and settings, please refer to Services Upgrade and Migration Guide, section "Migrating Websites from Legacy Linux Shared Hosting"