Ok, my last q ?
So basically you need to over dimension the cross section of the straps to get more stiffness in, like being much above the breaking limit where the strap does not oscillate/vibrate from dynamic loads ? Well in that case, considering the same cross sectional area what is the advantage of the rectangle cross section. Don't get me wrong, I understood all the other stuff (I guess), but this Q wasn't answered - the actual advantage of the rectangle cross section over the round one. The similar round section for the 90 sq mm area is an 11mm diam. rod.

And sorry about being off topic, and about bothering with this Q.