Well, I saw this too late to provide advice, but I am very happy with my decision to trade my cuse4 for the cuse8. I've only put a few hundred miles on it so far, but the ride seems smoother, more refined, and better balanced. I always felt that my '09 was a ruby red lemon, so that could account for part of the difference. Then, there are the small upgrades and changes, like the integrated GPS, iPod interface, upgraded speakers, adjustable lumbar support passenger backrest, working heated handgrips, more boot room, and zero first gear clunk. The ruby red color on my '09 was more flashy than the anniversary color, but it was time for a change. I liked the red '13, but it was too much like the '09. The anniversary colors are more understated, but it has a classy overall look - and I like the blacked out engine components.
Well, I hope that you have the same experience with your change & look forward to hearing what you think after you put on some miles.