That menu is only useful during the modem startup process. It helps shorten the sync process if there are some odd, non-standard setup on the provider side, such as multiple CMTSs and downstreams for multiple providers. One the modem is locked on the downstream the modem gets all its channel info from the CMTS.
I haven't seen any real use for those menus on any U.S. provider in years.
Most Cisco and Scientific Atlanta (bought by Cisco a few years ago) modems take a specific config option to set access to full the diagnostic menus. By default they're set to limited access unlike just about every other modem around. It's been that way for 12+ years and most users run into it on just about every ISP. It's the rare ISP that goes through the trouble to add the specific config option to open the diagnostic menus.--
Two is one, one is none. If it's important, back it up... Somethimes 99.999% availability isn't even good enough.