Well then you not correct, there is no way SL is stiffer the the MC, the highback has a crap ton more torsional flex where as the MC is solid. MC is also made out of carbon fiber which is rigid and responsive, the SL has a carved out asymmetrical high back. Until this year when the charger beats out everything in terms of stiffness the SL's were a step under the MC Metafuse. Google reviews of the MC and they will tell you what I am.
Like my original post said, I cant comment on the other parts of their line, so you may be right about those. But until the charger was redone this year the MC was top then came the SL.
Complete and utter horse shit. Even the Union reps (both Johan and George) on this site have clearly stated the opposite - e.g., here