For sure the physical editing changed style changed between Audio and Sonar, but I don't know if it got any better, just different.
However, that being said, there have been some great additions, such as the intensity of the color scaling with the velocity of the note. That one feature has had a great effect on my work (hopefully for the better). And now the velocity bars match the colors as well, woo-hoo!
The ability to see velocities of only selected notes is a big plus for me as well. I don't think that was in Audio?
The 3d look is a nice-to-have. Haha, that screen print from the OP, of the 3d-Not Audio screen brings back memories!
Still some clunkiness in Sonar that surprisingly have never changed since Audio, like the ponderous amount of work to select tracks, or, in the Screenset model, to KEEP tracks selected.
Also, sort of a cheat, but I devised a handful of CAL scripts back in Audio to assist my midi editing. They still run as expected in SPlat, so for that, the different editing models are non-issues. (As long as CAL keeps being my PAL!)
I guess, in my case, midi ENTRY (typically from a keyboard--the musical kind) ranks about the same either way, Audio or Sonar (although, Audio was a long time ago, and my memory only is reliable back to---wait, what day is it?). When it comes to midi EDITING, I have to give Splat the edge, there is more informative feedback about the events.