@chuck... Hi, dude. How are, ya?
I have indeed used the PRV and I am certainly not ragging on it. I will be using it quite often for multiple reasons, one of which is although I understand notation these days I am not as proficient as I'd like to be. Also PRV would be my go to for tweaking note lengths and volume/articulation. But that does not negate the usefulness of the notation staff (and that point actually doesn't have anything to do with Sonar or any other program. It is just the nature of the staff itself).
I'm not sure how in depth you understand notation or general theory principles (and it doesn't matter because I'm of the mindset that if it works for you then do it) but you must appreciate at the least how much screen space using the Staff View saves as well as enabling a smoother workflow because the notes are grouped more tightly together. Look at it this way.
In PRV all twelve chromatic notes are displayed stacked on top of each other. That is twelve separate lines of data just to achieve one octave. With the notation staff immediately you are cutting out five of those lines because instead of displaying all of the non sharp/flat notes we use key signatures and accidentals to represent those tones. Furthermore we are using the spaces AND lines to put our notes on as opposed to a space for every letter note. That makes it so we are using 4 spaces to achieve the same amount of tones the PRV needs 12 spaces to display. So that is one way the staff is more efficient.
Now probably the most important and beneficial reason to use the staff are key signatures and the concept of consecutive letter note names. Each key has 7 unique notes. These notes follow alphabetical order and no note is repeated or omitted. As you know each line and space on the staff represents one of these letter name notes in order. In C which has no sharps or flats you can easily just hum a bar and write it down on the staff if you are familiar with the steps/intervals of the key. Want a different key? Simply toss a key signature on the staff and use the appropriate letter note as your starting point. There is no guess work and you don't even have to have the specific note names memorized for every key. In PRV you do have to know that stuff or work through trial and error (unless you are a proficient keyboard player and have the key forms memorized I guess). Also in PRV the notes don't go consecutively right after another. You have to account for the spaces between each step of the scale which are sometimes there and sometimes not and that can make inputting (IMO) more difficult and cumbersome than on the staff.
There are a ton of other reasons like easily constructing and expressing chords, inversions, transposition, etc... but the above are a couple of the more useful characteristics of the notation staff. When it comes down to it it's just another tool but an extremely powerful one and it is the universally agreed upon language of music. It just makes sense to have it running as well as possible which from the sounds of things it is not. I've used the SV a couple of times so far for simple stuff and it works but it is certainly quirky and not very intuitive. I could see it becoming a real problem if I started getting a little more ambitious which is most definitely going to be happening... and soon.
Anyway, hopefully that clears up my views and probably some of the views of the folks who have been wanting an improvement as well. It really is hard to grasp how much easier notation can be compared to other input methods without fully understanding it. I think that's why we get this constant back and forth on the topic around here. It would be like if Cakewalk decided to let the PRV languish and become unusable for anything pro and instead put all the attention on the staff and then users who'd never used or understood the PRV dismissing those complaining. That would anger a lot of people and for good reason I think.
As I said though to me it's not a deal breaker and I'm certainly not bent out of shape about it but it sure would be nice to have a top notch notation input option. Hope that all makes sense. Cheers.