Whilst I'm not convinced by his calculations, his findings do actually tie in with mine.
As with most long in the tooth IT guys, there are things which we suffered back in the dark ages which have stuck with us for life. For me it was Seagate drive death... We're talking 400meg drives here! (Yes, that long ago). Unfortunately I was a field engineer at the time, and covered so many miles just to replaced dead Seagate drives that I still wouldn't use them for anything more than a doorstop! (Actually I lie... I took them apart and used the platters to hang from the plum tree to stop the pigeons eating all the buds).
When my data storage needs at home expanded to the point I really needed to think about redundancy, I opted for "special" raid edition drives, only to have two of them die within 12 hours of each other when I was away from home. They were 6 months old. Don't worry, I also had backups.
I replaced those drives with the next model up (went to 500gig from 400gig, but the same brand, and still specific raid drives), upgraded the power supply in the server that contained them, put it on a better, mains cleaning, inline UPS, and increased the air-flow.
This time the first drive failed after 4 months!
I then decided to start again. Dumped all the drives, working or not, and bought a load of cheap Fujitsu 1TB drives, plus a couple of spares... Never needed the spares. They were still running perfectly reliably when I replaced them with 2TB Fujitsu consumer drives... And that's where things are today. The 1TB drives have ended up being used in all sorts of machines, and I've never had a single one give the slightest hint of failure. The 2TB are still whizzing along in the RAID, the uptime of which is now over a year.
All the spares have been pinched for other things (really shouldn't do that!), such is the confidence they have given me.
Meanwhile, in the work environment, I've seen more specific raid drives die in under a year than I can remember... Some things don't change.