Just a quick reply, ProtoDie is completely correct. The pivot point for the steering arms is dictated by the arc the upper and lower arms describe and their (combined) linear length change as they describe this arc.
With a long lower and shorter upper arm they are each going to have a different arc and different length changes therefore requiring something of a compromise (to a degree) in the positioning of the rack ends.
Saying that you prefer this or that unit because this is easier to mount etc ignores the principle of bump steer and its minimisation. Bump steer isnt nice stuff and while some claim to have 'eliminated' it in their machines it is much more likely that they have minimised it.
IMO
