well, you certainly interpreted what I said wrong. By adding washers under the inner ball stud, you raise the ball stud thus lowering the RC.
I understand what the effects of RC location have to do with handling. What I don't understand is why you need a special block to lower the roll center when you could just as easily do it by adding washers...
Raising the RC will actually increase side bite. When you raise the RC, more weight is distributed to the outer wheel in a turn. This loads up the wheel and causes it to bite. The danger of a high RC, though, is what happens when that outside tire decides to let go. When it lets go, it's usually abrupt and not controllable.
A lower RC is the opposite. The weight is split more evenly across both tires. This is good on a low grip track because you're gonna loose traction no matter what you do, so you don't want it to be abrupt and uncontrollable when you do. A lower RC is what makes cars "rotate" in the corner. The outside tire is loaded up so the tires slide a bit.
I remember watching one of the losi videos and they discussed their RC blocks. It sounded like changing the block also changed the amount of "bind" in the suspension caused by the CVDs. I personally don't like the idea of using drive component bind to alter handling. It just sounds like using the wrong tool for the wrong job.