I wouldn't consider this as a backup solution, more as one for high-availability of data.

Please don't use this as your only backup. Consider it an experimental cross-machine RAID.

You'll adopt the oft-repeated "RAID isn't a backup" mantra as soon as any of these issues hit you (like several have hit me): https://photostructure.com/faq/raid-is-not-a-backup/#why-isn...