I know it to be a fact. The instrument's playability will improve your skill level.
This is true for me.. My skills are better playing the G70, interaction of keys to sound and the comfort of a more natural response. Compared to the EA7, I can feel and hear the difference when I play each one..

If I play the G70 for any extended time, it is hard to want to play the EA7.


So yes an instrument can and will definitely improve your playing skill.