Huh? (sorry - long post)
OK, I think perspective is being lost here. First, the SC was the FLAGSHIP for the entire Lexus line when it was introduced. It, not the LS, was the most expensive product Toyota marketed in the US. To assume they wouldn't put the optimum brake package on the flagship model without having a REALLY good reason isn't sensible. The car doesn't just exist as a platform to carry around brakes - it needs to do a bunch of other things well, like ride comfortably, handle well, accelerate well etc. One possible clue to why the beloved LS brake "upgrade" may not be an upgrade at all is shown earlier in this thread. Unless there's a misprint, the SC rotor weighs less than HALF the LS rotor. I don't know the respective weights of the calipers, but I'm quite certain the LS calipers are also much heavier. If you compare the weights of the requisite larger wheels to 16 inch wheels, you're gonna get another shock. One of the cardinal rules of design is to minimize unsprung weight. But even more significant is to minimize unsprung ROTATING weight. Rotating weight creates dramatically higher gyroscopic forces, as well as flywheel effect, which don't do anything good and create lots of bad effects.
Additionally, bigger pads are not always better. Brake fade and loss of braking effectiveness result from gas production as pad material breaks down. Getting rid of those gaseous byproducts is what makes cross drilled and/or slotted rotors helpful in racing applications. Solid rotors and larger pads may be a good match in a heavy car that is not likely to be driven in a spirited manner (like the LS), but not necessarily in a sportier car like the SC.
Also, to continue with the skeptical theme, unless I see actual controlled braking distance measurements, I'm not convinced. First, most comparisons are between clapped-out stock systems to LS systems with new pads etc. rather than optimized stock vs. optimized LS. Second, perceived stopping power may not indicate ACTUAL stopping power. Higher initial grab may FEEL like more powerful brakes, but actual braking distances may be longer. Parking lot braking vs. mountain road braking are two really different things. Autocrossing vs. Road America also.
