Tire durability includes several components. These are puncture resistance, cut resistance, wear resistance and resistance to aging and weathering.
I haven't had a chance to road test Specialized Armadillo tires for all these qualities. For some reason, our shop does not stock the Specialized tire line at this time.
A few years ago we had a bundle of Armadillo tires in about 700X25. They had an incredibly stiff sidewall and thick tread. Unfortunately, they were too narrow for the kind of rider who could really use them around here. The bike path in town is not paved, and most riders don't feel secure running a skinny tire on it. The road riders who wanted a flat-resistant tire decided thay wanted something lighter and more supple more than they wanted the bullet-proof puncture resistance of the Armadillo.
Because I haven't seen recent versions, I don't know how much Specialized has improved the line. Very early tires with the Armadillo designation were much like the other high-pressure road tires at the time, in shape and feel. This is in the 1990s. I don't know if they were as durable as the newer versions.
The really stiff ones we had in stock just before the turn of the century, with red sidewalls, were a little hard to mount and remove by hand because of their stiffness. Again, I don't know if that is still true.
Armadillos we mounted then did not seem exceptionally resistant to weathering and age. We replaced one set for a woman who had not put a lot of mileage on them, because the tread rubber was separating from the casing. This happens with many tires if they get left to dry out. When different rubber compounds are used, you will see that they often age differently, even if they're the same color.
The best way to get your money's worth out of a tire is to ride it a lot. Failing that, hang your bike indoors, preferably safe from extremes of temperature and humidity, and direct sunlight.
The IRC Tandem tire has performed extremely well for me in all aspects of durability. I've gotten long mileage, ridden over a fair amount of sharp stuff, and had it on the bike for more than a year (Possibly much more. I can't remember whether I put it on in spring 2005 or the fall before that.) I always park indoors, so it's been babied to that extent, but it also sees a lot of dirt roads, occasional trails and miles of pavement. So keep it in mind as a possibility, even if it's not your first choice.