OK, I've been recalcitrant adding my 2 cents, but I'm impressed with the length of this thread! I would greatly prefer to work in standard notation when composing, but the staff view is not nearly full-featured enough. Working in an external notation program and then importing into Sonar is, for me, a terrible workflow. If the staff view had most of the capabilities of Presonus Notion, I would be very happy.
But I can see where there are serious programming obstacles to accomplishing something like that. The PRV is much more suitable for making the minute edits required to get things to sound just right. Doing that kind of tweaking in a notation program is very difficult, or it is for me anyway.
That said, I'd love to see at least some improvements in the staff view to where it would be at least more suitable for initial note entry.