Is there any place it's specifically stated how sensitive the new S1/S2 driver is? All I know of it is that it's based on
this driver, which isn't particularly efficient.
Also worth noting, low end efficiency is largely dictated by the enclosure volume. AFAIK, the new S1 is ~3.5 cubes, with the new S2 presumably running around 7 cubes. The Deep Sea 24" subs are a bit larger at ~8.5 cubic feet.