Digikam can do raw. In the article the author says "For KDE users (or Gnome users who don’t mind installing a bunch of KDE dependencies), digiKam is also a great option to complete several of the functions I mention here. If KDE is your cup of tea, check it out."
I don't remember if I used Ubuntu Software Centre or Synaptic to install Digikam (onto Ubuntu 12.04/Unity) but I'm sure that whatever I used, it sorted out all the dependencies for me. The Digikam website says that it is an application for Linux, Windows, and Mac-OSX though I've never tried it with Win or Mac, I understand that the installation process is quite involved (for non Linux readers, installing it in Ubuntu Linux is a simple couple-of-clicks operation).
I'm very much an amateur/beginner with PP and my Gimp skills don't stretch to me missing adjustment layers nor does my technical ability stretch to writing python plug-ins.