Importing a device set is useful if you are sharing information with others. If someone has already created a device set, you can import the set instead of recreating the same set on your computer.
When you share a device set by importing it, Adobe Device Central does not import the actual device profiles (XML files including all the respective device data). Adobe Device Central imports only the information about which devices are included in the project set. If you do not have all of the device profiles in your version of Adobe Device Central, you are alerted that you must run an update to obtain the missing profiles.