Had this topic come up in a forum thread the other day and there was lots of heated debate over it. Looking for views from users here - it's fully hypothetical because it doesn't matter to anyone but the end user.
I use servers with excess drive bays and can use SAS drives so I'm happy with keeping backups as normal and using cheaper ex-enterprise drives in RAID1/5/6, these also typically have much higher MTBF figures compared to consumer drives which you might buy new plus you can get new drives that are lemons anyway, same as if you buy a used drive from a dodgy source it can also be DOA. I know MTBF isn't the most useful specification when buying drives.
Wondered what others think of this? There probably isn't a single right answer anyway, I'm curious more than anything.