Originally Posted by
box opener
when the chain is under increased tension will friction shifter make better shifting？
It can, since you can easily push the lever a "little more", and force a shift if needed.
The whole idea is that you push (or pull) the lever UNTIL it shifts, so it's just a matter of YOUR skill and you/shifter ergonomics.
Ergonomics can have a major impact on shift quality.
When I had friction on my Rockhopper, my shifting got better as I went from 7 to 8 to 9 speed. The amount of "push" needed better matched MY shifter ergonomics with MY hand.