More on Atomic slalomsAnd if that weren't confusing enough, Atomic also makes another slalom ski, the SL:9 which also has an 11m sidecut at 160cm.
My assumption is that (1) SL:11 is a demanding, REALLY stiff slalom ski with a 14m sidecut to be used like the World Cup racers do, speed speed speed, and worked furiously to generate the force vector to decamber the ski to make the turns (2) SL:9 is the less demanding slalom racing ski that the rest of us should be on, with an 11m sidecut and more flex, a lot more user friendly, and (3) ST:11 is more user friendly still (Atomic says its "the ultimate weapon for citizen racers, or diehard skiers who just love to turn," e.g., more fun and user friendly still, rather than ultimate performance machine.)
I don't really know the big difference between the SL:9 and the ST:11, but my brother just got a pair of ST:11s for this season, to race slalom on. Last year he was on a pair of SL 11.12s, and he has been looking forward to an 11m sidecut instead of 12m sidecut, and a less stiff ski. (The Tichys are big on telling most club and masters racers that, since we're not on the World Cup, that we're usually skiing on skis that are too stiff for ideal performance at our level, having chosen ego over appropriate flex for the actual G forces we generate.)