Kimmo- I wish that manufacturing was spot on, every time, at every cost level. But i work in the real world and it's not. Pulley float might effect shift response. But unless the guide pulley is well worn, I see far more cable friction reasons for shifting issues. The floating pulley helps make real systems more consistent, IME.

It seems like we share the dislike of internal cable routing or full length casing.

While I run a Shiftmate on many of my bikes, have done so for over 10,000 miles, I will say it does add a pause into the system. But it also does allow combining levers, ders and cassettes to the choices that work for you. Andy.