For most people it's better to make a nightly copy to other HD. Raid is for saving downtime on HD failures, doesn't save you from accidental rm -r, word processor corrupting your thesis, GPU driver crash corrupting your filesystem, box getting owned, etc.
i think what he means is, down time isn't a big deal since recovering from back up is quick enough in his case. I never found raid 5 particularly helpful because:
#1 hard disks tend to fail at the same time
#2 systems fail to give warnings on bad disks ie everything is working, no red flashing lights, things go boom, restart, just kidding, lol you got 2 bad disks.
#3 redundant servers > redundant disks for uptime
#4 cloud
For most people it's better to make a nightly copy to other HD. Raid is for saving downtime on HD failures, doesn't save you from accidental rm -r, word processor corrupting your thesis, GPU driver crash corrupting your filesystem, box getting owned, etc.