I have the rear only set on the stiffest setting. Really completed the car for me suspension wise. I had my BC coilovers for a few months before I got the bar and it was still an improvement over stock. It more than makes up for the softer spring rates in the rear with all the coilover options for our car. Highly recommended!
I have mine on the stiffest setting with otherwise stock setting and it completely neutralized the handling. Oversteer when I want it to, neutral when I don't. Very easy car to drive at the limit now.
I have my Hotchkis RSB set on less stiff, which is equivalent to the COBB on stiffest, and it stays planted when pushing it. But this isn't my first rodeo in a FWD car, either. Avoid lift-throttle oversteer when testing the limits on tight turns.
I have my Hotchkiss set on "less stiff" also. Keep in mind, that there is nothing wrong with putting one end link in the more stiff position and the other in the "less stiff" position. You will get an intermediate setting.