Just a forwarning, you will run into things that break running Sabayon-limbo.
There aren't (as of yet anyway) any repos for entropy that contain just the latest KDE (or any other DE or set of applications). So by jumping to limbo, you aren't just upgrading KDE, you're upgrading everything to things that are not fully tested out.
There's nothing wrong with doing so, mind you. Just as long as you understand that things will break from time to time by doing what you are doing.
KDE is mostly making incremental changes at the moment anyway, so unless you are running into a specific bug that has been fixed, there's little reason to rush ahead and get the latest before it's been tested. (Just my two cents.)