Soft bar. They took what has been proven in rally (and other types of offroad) racing and applied it to "crawling". If you understand how a torsional anti-roll bar works and you know the different effects of hard to soft to super-soft bars, it's easy to understand the what and the why.
What you would get with "x" amount of spring rate and length, on a vehicle with a soft or super-soft bar is a flatter plane in regards to vehicle roll, which creates stability. The softness of the bar and the spring rates determine how much movement or "articulation" you will see within that setup. All else being equal, when you find the sweet spot of rate for bar and springs you could have the best of both worlds, thereby making it "better".