Would be handy so that pre-existing devices don’t get wiped out when adding a saved device chain.
When loading a file from the Disk Browser, you can right-click and choose “Load File with Options” to get more options.
For device chains, you can choose whether the loaded chain will replace the existing one, or append to the end of it instead.
References:
http://tutorials.renoise.com/wiki/Disk_Browser#File_Panel
http://tutorials.renoise.com/wiki/Preferences#Files