This has been a very helpful thread. I now know that the ONLY way to get a full backup is to configure the settings in Kobo Utlities first. Simply gonig through the menu and selecting "Database>backup database does not work. It does create an sqlite file, the size indicates it most likely IS a copy of the KoboReader.sqlite on the device, but it does not even NAME it, at all. It also does not copy any config files. Had I not started this thread I wouls have gone on virtuously creating "backup" files that were effectively useless.
I'm also grateful for the suggestion to restart the device befoe connecting. I never used to, but given the increasing frequency of database errors I'm having, doing so seems like the course of prudence. I want my Sage to last until the new Carta 1400 400 dpi Sage with 3GHz CPU, voice commands and a 75 gram 10000 mAh battery comes out in August. Of course, it won't have the very latest Adobe RMSDK