hmmm,
My understanding of bump steer is when the inner/outer steering tie rods do not follow the same arc as the lower control arm for a Mcpherson strut. I.e in bump the diffence in lower control arm arc to streering arc causes a steering input.

The "bumpsteer spacers" i have seen (eg maddat) that go between the lower control arm and strut (i.e space the strut further away from the steering arm and ball joint/lower control arm but do not change the spacing of the steering arm to lower control arm), in theory (and I could be wrong) don't change the arc path of either the lower control arm or steering tie rods in isolation, therefor do not effect bump steer.

This type of spacer will have an effect on the Roll centre by raising it up (closer to CoG - as stated by Benny).
When the LCA moves past horizontal it has a changing effect to the wheel camber, i.e during compression you get an increase in neg camber unitl horizontal then past that point the camber starts to decrease (tend back towards 0).
I will have another look at "race car vehicle dynamics" tonight to confirm.

As for the original question if there is a problem with Bump steer you need to change to LCA to steering arm arc either by changing the length of the LCA, moving the inner LCA mounting point or the steering arm inner tie rod mounting point or changing the outer steering tie rod location (ie new steering arm geometry).

Bryan