Upload & Sell: Off
RAID1 sounds nice in theory, in that its automatically creating a 2nd copy of what was placed on the 1st drive. This also means that if you delete a file, it's also deleted on your "backup", and if a file is corrupted, the corruption is also transfered to the next drive. I've had corruption issues with RAID1 setups, and it's just a risk I'd rather avoid.
The only thing its good for is immediate protection against drive failure. If you are diligently backing up your files to other drives/locations, then I don't see a real need for RAID1 for photographers, because you don't need 100% system access 24/7. It's not going to hurt to throw in a non-RAID clone that takes 5mins. Will I lose some files in the process? Potentially, because it's not backed up 100%. But it the RAID takes up space (if you only have 4-5 direct sata connections) in the computer, and requires more power as well.
But RAID1 is FAR from being the best backup system, and I wouldn't really even consider it a backup system, for the reasons above.
The last thing I think photographers should do is run out, get an extra drive, setup RAID1 and think they are protected. A good backup strategy involves much more than that.