This could be a tricky one.

If you switch a stave view to piano roll and edit it, their are two options with what you do with the edited part. 1. Don't change what's on the original stave rhythm-wise (note placement and length), but accept pitch changes, or 2. Recalculate new note placements and lengths and redisplay them on the stave, including pitch changes also. The first option is more for changing playback; for example, blending two notes together using a length adjustment to trigger a legato sample.

In Cubase, a piano roll can be coverted to notation and you can clean up the notation without affecting the original track. This is usually only to do with note placing and length. Eg. Visual quantisation.

Especially for playback in Notion, there'd be times when I would want to fiddle with note placement and length (on something like a piano roll display) to manipulate playback, but not necessarily change the score on the stave. Re my previous post on drawing midi data curves, under the piano roll might be a place to draw the curves. Still better, in my opinion, to have box open under a stave to do it though.

All these suggestions are to do with using Notion as a writing tool with good live playback. This is what I use it for all of the time. I use it over Finale and Sibelius, both if which I own.

Thanks for a good product!