Thank you for the detailed response!
I think this might be a dealbreaker unfortunately. Ideally I was hoping for something similar to RAID 1, where data is still readable/writable if one of the mirrored drives goes offline. I realize that it would be easy to remove a drive from the pool, but not everyone working at this business would have have skills to do that and that would result in downtime if the person with that knowledge wasn’t working at that time.