I am a big supporter in a color customizing changing from the battleship grey to something more customizable.
BUT...with that being said, colors are a very small part of what the software is used for, the color customizing in preferences is very in-depth. you can change a lot of things if you take the time to get in to it.
but Sonar is not photoshop, its not a graphics editor, its meant to do a few things and do them well. Record music, Use Synths, Plug ins, Amp sims, exc.
there are options out there like Duck bar but what I found is the more I get in to customizing (changing all my colors),
i get distracted and further away from the thing I sat down to do in the first place.
Make Music.