Any time you reduce the shift throw, the effort to shift will become proportionally harder. This is true of any short shifter. If the design is such that there is a lot of friction, it will make things harder.
Our bushings make shifting slightly easier because the spherical bearing removes the compliance in the OEM rubber bushings that you would normally have to work against. However, it's likely that they will not reduce shift effort so much as to fully compensate by the extra effort your short shifter is requiring.
~russ