Very practical approach. I will leave the box abroad at Debian 8. But I also understand from this, that the May 31st version is NOT tied to Debian 8 - there are no optimizations or required file modifications that will be over-written during an upgrade to Stretch and prevent me from upgrading my Amlogic boxes to Debian 9 back home.
Another question; I tried the 'nand-sata-install' in order to get my micro-SD card with me back home. But even though it was a successful transfer, according to the terminal output, the box fails on boot. I googled around, and I can't find any documentation of/experiences with Amlogic boxes automagically working with Balbes Armbian eMMC installs. Have I missed something, or is transferring to eMMC dependent on more than the nand-sata-install method? The box ran LibreElec prior to transferring Armbian/Debian, by the way.
EDIT: Seems I bricked the S905. It powers on, but nothing is output to screen, no DHCP attempt via ethernet is made. It's just...dead, except for the blue light Doesn't respond to tooth pick boot via USB/SD card, either. Does anyone have a link to a resurrection tutorial for unbricking the trusty S905 after eMMC install? I had no luck with the Amlogic burn tool - images don't 'stick'. Nor did TWRPing via USB (before bricking). Can't even detect the device when USB connected to my Lubuntu PC. Guess U-boot or similar low-level requirement is gone. Luckily, I have extras brought along, but still want to revive the little trooper...