I think I've failed to communicate a key point. Each of these changes is an adjustment. Rear roll rate is most sensitive to seemingly small changes. Addition of a rear sway bar is a major change. When used, it should be a part of an overall development. Key word here is development. A good suspension has to be worked out in practice, not just theory. It starts with the tires and road conditions. A car that's going to be driven in snow and dirt, even Hekkapallita rally tires, is going to need softer springing and accept more roll to maintain grip than a car running a high speed track on dry pavement.
Folks can argue all they want. Some may have jacked up the rears with different size tires or high arch springs. Others have bought and installed an item, and are sure that is the way everyone should do it. The folks making the arms think they are the best thing since sliced bread.
You can get more adjustment as needed much more cheaply. One is by using Moog 'problem solver' UCA bushings to your advantage. Another is with hardened washers to shim out the lower ball joint to spindle. But the first thing is to start with the lowest factory ride height. Or, if you're want, go a little lower. This will start your car deeper in the negative camber and more into the positive caster.
For street use, street tires, the camber requirements aren't that radical. If you're going on track with competition or near competition tires, that's a different story. Then start with the specs recommended by that tire's manufacturer.
My suggestion is not buy into marketing or looks. Find people and cars with actual development time. I gave you the links above for that reason.
