RAID 1 never paid off in over 10 years.
I won't tell much over 10 years. Here's the story. I watched for years as people tried RAID 1 to save their behinds from failed drives. Sadly I never found it to pay off in decades. The issues of user error, virus, pest and worms actually made RAID 1 a liability since many (misinformed) owners thought it was a backup in realtime. Yes, it was. As soon as an error occurred it was faithfully duplicated in the RAID 1 mirror drive.
To double the trouble the owner who thought it was a backup discontinued making backups offline to tape or disks.
I'm sure there is one success story out there but in decades I've never encounted one.
-> If you had RAID 5 I will write I've seen that work, but they had a few dozen drives on that system.
Maybe it's time to give up RAID 1 for speed and occasionally backup.