Both editions have it as a great light weight alternative. The menu is customized enough to allow access to several applications including Konsole, no dead entries. It's a good start and if you want to use it full time you can add the rest later.
I found going into Fluxbox on the KDE spin gave me the responsiveness that I had been looking for, and you can still have all your preferred applications just a click or a run command away.
|Sabayon 6 KDE with Gwenview open in Fluxbox|
So I think for me personally, installing the KDE edition and then running Chromium, VLC and Clementine from Fluxbox is the preferred option. It's also enough to launch the media center if you want to use it mainly for that and just on the side sometimes a bit of browsing or as a back up PC, instead of going for the full on option with XBMC only install. Not to forget it can be run from DVD if you prefer that and only reboot your machine once a year. Or perhaps Sabayon SpinBase could be put to good use here to build a stripped down image.
|Media center in full screen|
When I set out to test Sabayon I had only planned to do a quick overview of the GNOME edition. I ended up downloading the KDE 4 spin and came to the point where I am seriously considering building a media server with it. That's how intriguing this distribution is. It's not perfect, but it's seriously fun to explore and play with.
Part 1: Sabayon 6 GNOME
Part 2: Sabayon 6 KDE