ZFS or BTRF mirror will know which side is at fault due to checksums. I’m more concern about simultaneous falures of two disks. Rebuilding of a RAID puts lots of pressure on remaining disks, so probability that remaining one dies too is much higher. with RAID6 3 disks need to die to lost date, which is less likely but not impossible.
Look how much any maintenance/repairs costs now. It may be true.