Eh, I overclock. Stabilty > speed, but stability + speed > just stability. Hard to argue with an extra 500 mhz on an A64 when it's running rock solid. Might reduce lifespan some, though I'm not giving it extra volts so this risk isn't too great. And by the time the overclock would caused reduced lifespan, the thing will be obsolete 6 different ways to sunday.
These guys though....they don't care. Lifespan doesn't matter, temperature doesn't matter, and actual performance doesn't matter cause it ain't gonna be usable at that speed for any length of time. Just a matter of "Is it gonna be stable long enough to get the CPU-z verification and maybe a quick superpi run to extend my e-penis."