I upgraded my N100 with ZFS and tunables yesterday and so far so good. For the first time, I used the Upgrade from Console option just to try it out, and it went smoothly and rebooted the device successfully.
Upgraded successfully on my device from 25.1.10 to 25.1.12 to 25.7 to 25.7.2 yesterday. n100 hw not from the major N100 vendors. A bit concerned with bootloader and successfully used the search in 25.7 series "bootloader" to use the github tool https://github.com/Emrion/uploaders. It is a safe tool to update the bootloader at this moment.