Bogart, thanks for the detailed response.
I did some search and found a good post on swaybar stiffness and understeer here:
http://www.e90post.com/forums/showthread.php?t=531711
"Unlike double wishbone type suspension, the MacPherson strut has an unfavorable camber curve, in that the camber does not increase linearly as the suspension is compressed. So as the car takes a corner and sets, the outside suspension is going to compress past the roll center and will go from a favorable increase in negative camber to start to lose the negative camber. When that happens the front end will lose grip rapidly. One of the solutions to alleviate this problem, is to deploy thicker front anti-roll bars to prevent the outside suspension component from compressing PAST the roll center and start to lose camber."