Could be blowing smoke but no reason to, he went back to the centre raving about it. Personally, I prefer my S1 largely because the S2 just feels heavy and the brakes lack feel.
Of course, the point is that all set ups are about compromise. So a suspension that is best for a track may not not be best for high speed lane change, alpine circuit, split friction surfaces, negative camber, handling circuit, low friction surface…all of which you get at Millbook.
Also, it is all about decreasing returns, any one improvement may make a change, but the second, third and forth all less so.
Back on thread, I would expect the shear panel gets most of what can be gained from rear subframe stiffness.
