the disk db is nice so you can still use all your apps while your internet is down, but this might only be useful if you are building a microapp browser.
Discussion
It's only useful if the app is getting killed too many times. Otherwise, in-memory relay does work offline too ( albeit we never really focused too much development on it ).
In most normal cases, Android will put the RAM of the app in zRAM to free memory for other apps and recovering that when the user brings the app back from background.
My heavy user for instance only sees an app restart with clear db once a month or so.