Having good shifting up the cassette but not down, or the opposite, are often from things like bent hangers or friction prone cable routing. If the shifting in the well working direction was good with each shift, so that the 1 to 2 shift was as well indexed as the 6 to 7 shift then the cable pull ratio of the der is correct for the rest of the system.

BTW there are 9 speed Shadow ders that share the same cable pull ratio as the previous non Shadow 9 speed ders. However the amount of open chain between the top of the guide pulley and the underside of the cassette cogs will sometimes grow and shrink to a greater degree with a Shadow der (as the guide pulley shares it's axis with the cage pivot). Cages with their guide pulley axis off center from the cage pivot can, with good design, allow the guide pulley to maintain a more consistent distance from the cogs. Andy.