Actually you do not need to install Evox to backup discs. What you can do is download the DHCP version of Evox. Burn that to a disc. You can boot your XBOX with that disc!
After booting to Evox, you can take the Evox disc out, put the game disc in and transfer the contents of the game disc over your network (using FTP).
You can also put other apps on your XBOX HD and use the Evox bootdisk to access them. If you configure Evox to update certain folders automatically (e.g. for applications) you don't need to hassle to access certain folders through disk explorers etc.
There is so much possible, it just depends on what you really want