like i said, it all depends on the type of sound you like. metal cones are more accurate but that usually means they are more harsh as well. if you are actually an SQ person then you will have the means to EQ and take that harshness down to eliminate ear fatigue. but some people like the bright sound. they are not meant to be beaten all to hell like an SPL woofer. so if you do that, its your fault you folded the cone, not the speaker's. its just the nature of metal, it doesnt flex so much until it becomes a bend and it doesnt go back to its original shape. the paper actually flexes more, but it wont bend and it does go back to its original shape. its not an engineering thing, thats just how those two materials react.
if you know what your doing cone resonance means nothing, especially if you know how high the freq it resonates at