Bringing this one back from the dead.
Found a good "suspension walkaround" from Edmunds.com on both the M3 and 135i. You can see some of the suspension differences here, and can be useful for some people to visualize the differences:
M3:
http://blogs.edmunds.com/roadtests/2...ound.html#more
135i:
http://blogs.edmunds.com/roadtests/2...alkaround.html