if you expect downtime in the 5 year to replace fan and whatnot, you're not getting 100% of your money/perf back - and I didn't see that in the article.

if you have spares, spares need to be in the cost, and value lost to downtime stay minimal. but you have to include spares in the expenses. if you don't have spares, 1-2 day downtime is going to be a decent hit to value.