TIre life expectancy - is there a range?

Nope, the 2,000-10,000 is more realistic. You've got such a wide range because you have a wide range of different rubber compounds used in the different brands of tires, nearly every model is going to wear a little different. I've had some that have lost the outer tread in less than 1,000 miles and some that show little wear after 5,000.

In running shoes, it's the cushioning that breaks down, not the tread.

Armadillos are "tougher" because they have puncture-resistant bead-to-bead casing, not necessarily because the outer tread is longer lasting.

 I've heard many good things about the Armadillos esp for NYC riding and I hope you have better luck w/ them but I think a lot of it is just that, luck. I was gonna switch to them too bc the Michelin PR2's I got flatted often when I first got them. Since then I've gone quite a few hundred miles with better luck. My point is, it's often the  roads not the tires that cause the flats (like cabs aren't enough fornus  to worry about!)

Never mind. I don't know what I am talking about.