[Excaliber]

My Excalibur would twist like a pretzel if you picked up one corner, for a frame chasis stiffness test, thats good enough for me.

My ERA is incredibly stiff, pick up one corner and the whole car moves with it. Never had the chance to jack up an SPF.

Point is: The strength comes from how it is built more than the material thats being used. A square frame or a round can easily twist if it isn't designed properly. Seems pretty clear though that sqaure is stronger than round over all.