So you mean to say you use your NSS M1 "Pig" vacuum as your daily driver? I guess you like a vacuum that wastes electricity. I just can't see a need for a vacuum that uses all that amperage, and does the same job. You're right, in saying alot of Orecks will not last 20 years - those are the ones that get used and ABUSED. I've even had Orecks come in that vacuumed up dog sh--. I even pulled a thong out of an Oreck once. If you really tried, you could destroy an NSS "Pig" vacuum as well. However, I've seen many Orecks that have lasted the 20 years and then some. Like I say, the one I use on a regular basis is 22 years old, still has the original motor, fan, and fan housing and works great. I've even got some of the original XL-4000's that are 40 years old and still work.
"For the price of two Oreck XL-21's, you could get a Kirby Sentria with attachments/shampooer" - yes you're right about that. And that's fine for you and me, but most people today do not want to be bother schlepping a Kirby up and down stairs. When the Tech Drive is off, the unit is extremely heavy to transport, and how many people do you know of who actually use the shampooer? I just found a Kirby G5 thrown out in Jamaica, Queens with the shampooer never touched. Alot of people have difficulty even converting the vacuum to tool use. I've gotten several Kirby Generation 3's (among others) as trade-ins on new XL-21's.
Interesting story about the metaxalloy "kevlar" fans. Oreck switched to metaxalloy in 1998 for the new Millenium 2000 series machines. I was invited to the factory to watch an interesting demonstration where they shot through the fan with a 12-gauge shotgun. It left a clean hole in the fan, but the fan itself did not warp whatsoever. So even if a coin or a nail does hit the fan, worst that will happen is the fan housing breaks. If you're going to be vacuuming up such materials, you really should use a shop vac, or at the very least, the Buster B that came with the upright.