I am not sure about what each one is rated. I would suggest looking for bike reviews on competitor for information such as stiffness and handing. When you find the information you are looking for, go out and ride both. Just because a review or another rider says a bike is "L" doesn't mean it will be for you. You could ride that same bike they said is "L" and think it is "G" or "Z." There are generally multiple frames that will comply with a persons fit parameters. By riding them you will know which is the perfect fit for you, numbers aside.

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"Just don’t abandon everything you’ve ever learned because of something someone said on the internet." - Eric McGinnis

I doubt you'd discern a huge difference between the two in the stiffness/handling department. As for aerodynamic performance, I think it's a pretty safe guess that the SC has the edge.