Exactly the opposite, I think -- clad coins seem harder than silver, and I believe they wear more slowly. They do wear, though; the outer layers of a clad coin are 75% copper and 25% nickel, the same composition as the nickel five-cent piece. And if you've ever seen a bin of Buffalo or Liberty nickels, you'll understand that they definitely wear.
No. There are numerous reasons they hold up so well but in recent years it's primarily the fact that their velocity has slowed remarkably. Back in the 70's a clad quarter was being spent more than three times a month but it's less than half that now. But clad's a little lighter which helps them not wear out since the pressure on them when they colide with other objects is lower. When they're being rubbed together in counting machines there's less weight to tear metal off the surfaces. One of the big reasons they don't wear out is that the 75% copper/ 25% nickel surfaces are much harder and stronger than silver which is soft. Of course there's also the fact that fewer people carry coins in their pants pockets now which combined with physical work used to be a major factor in wearing coins smooth. A workman could wear a pocketfull of coins from Unc to XF+ in a single day of hard work. Now they have machines to dig ditches. In 1957 when I started collecting it wasn't unusual to see 1932 quarters worn nearly smooth. This was only a 25 year old coin. Now 1965 quarters which are nearly twice as old are rarely lower than G+ or G. Dimes are usually lost or destroyed before they even wear down to VG.
No doubt about the fact that there millions of clad coins in circulation than there was silver in its day. They are more resilient because they don't see the heavy use.
