From this photo.........
http://www.flickr.com/photos/faasdant/6366344269/You can see that the line through the steering axis (would be kingpin on a trad) hits the road inboard of the tyre contact patch. This creates a positive scrub radius, which was common in cars until ABS and split braking circuits became the norm. In fact I recall that Audi were the first to promote negative scrub, which is more stable in the event of partial brake failure or a tyre deflation. Positive scrub lets the tyre roil around the steering axis when steering so in theory is lighter than close to zero scrub, but kickback is also a feature. This is not the same thing as bump steer, which as already posted above in this post is about track rod inclination, and toe in/out on bump/rebound.
The other interesting feature is the reclining damper angle. Ideally dampers should be as close to vertical as possible. Where MGB's have been fitted with IRS using Sierra 4x4 rear diff,the rear dampers are steeply inclined and I know of at least one case where the damper rod snapped as a result of the geometry. Maybe it started out slightly out of true. I also read this week that where the spring is inclined, it gives a falling spring rate under bump, which usually means a higher rated spring than if the same installation was vertical. So as in any installation, there are compromises. To reduce kickback you really need a tyre contact point close to the steering axis - so more wheel inset if all else stays the same, but this will increase steering weight at low speed.
