Staff View: all that has been said, but also: Don't lose the good things it already has, especially, infinite horizontal and vertical scrolling. I mention this because of the suggestion that you might incorporate Overture to replace Staff View. If so, this scrolling capability is paramount in my workflow. It's how I edit, I don't use PRV. Also, please keep Step Record, I use that , along with direct placement of notes.
My only other suggestion at the moment is to continue to let us customize the view. I prefer the GUI of 8.5 Sonar. I like to switch between full-size pages of Staff View, Event List, Track View and Console View.
And please keep Event List! I recently tried Home Studio, and it doesn't have it. I tried using PRV for a couple of weeks, but it's just not for me. I absolutely need Event List. Just keep all the classic views of Sonar, and let me decide how to use them.
Many, Many Thanks!