My views as a writer and publisher are different. While there have been no formal studies to confirm, observations with myself and those I teach show that a major component of learning music and building up musical memories is through eye/hand coordination, e.g., writing music down. The ability to write and review is an important component of composition, whether it's a song or a concert work. There IS something about sitting at a real piano with a pad, pen or pencil, to work out your ideas, and later the full breadth of them without being dependent upon electricity, recalling which version of the program you originally wrote it in and will it import into the new version, hard drive crashes, brown outs, et al.

When I get to teach orchestration, I don't let my students do their score reductions in any notation program. I used to, but then I found that a majority of their time was being spent learning the program so they could do the reductions (and later MIDI mockups) rather than actually doing score analysis and reduction and building critical thinking skills.

As to how music notation impacts musicians, clarity and elegance of layouts are enticements to perform and speak to the competency of the one composing the music.