I'd ignore it entirely, yes. Because I doubt that composers obey the 20msec/480msec duty cycle spec \:\) .

Now of course if you found two amps that had the same specs, price, etc but one had higher dynamic power, buy that one. That's what I mean by a secondary spec.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated