While X3 looks quite promising, has there been any change (good, bad, or different) in the behavior, functionality, or appearance of the Staff View?

None.  See my earlier post here http://forum.cakewalk.com/Dissapointment-at-IMSTA-m2896545.aspx
 

sergiobklyn
None.  See my earlier post here http://forum.cakewalk.com/Dissapointment-at-IMSTA-m2896545.aspx
 

Sorry, I didn't see your post.  I will express my disappointment there.

One thing I've noticed in X3a Staff View that has changed (that I'm not sure I like) is once notes are selected, you can't click off them to deselect (like in X2a)
You have to select other notes to deselect them. I work a lot in Staff View, and it's really taking a lot of getting used to, this new behaviour.
Or is there a new default setting for note selection I can't find ?