Raising the roll center (arm blocks) will LOWER the amount of roll (rotational force) applied to the tires. So, going from 0B to 3B all around will produce less of this force. It doesn't actually "stiffen" the suspension. It seems like in most typical conditions, a car will like a given arm mount (say 0B all around) and you tune with the other options, like the upper link, droop, shocks, etc......
There are always a number of things..... certain grip levels, different tires, layouts, track conditions that affect it... even driving style to a certain degree.
Going up to 3B won't necessarily take away traction..... in fact I've had issues with traction rolling and actually going down to 0B with more droop fixed it, because of how it loaded the tires and controlled those forces. It's all about mechanical grip and weight distribution
I have noticed 3Bs all around on the 6 can work well in low grip if you are a point-n-shoot kind of driver.
If I am wrong on anything, please chime in and correct me!
