Well, Mepis is a KDE Distro made by Warren and friends.
AntiX is a Icewm and Fluxbox and Rox Pinboard Distro made by Anticapitalista and friends.
Antix is very tweakable. You can run KDE, XFCE, Gnome Desktops also if you wish running the meta package installer. Antix also is a very fast running distro. I prefer it to lets say Ubuntu for speed but has the debian repositories (lenny,squeeze,sid, depending on how your repositories are set up and how adventurous you are). Anticapitalistas motto fits real well for this distro
"antiX "Tȟaš˙ŋke Witkˇ", "Intifada!", "Toussaint Louverture", "VET╦VENDOSJE!", "Lysistrata" and "Spartacus" - all lean and mean."
AntiX runs lighter applications than Mepis for certain tasks.Antix also has certain tools that are quite neat like sxmi script for updating kernel and packages besides the regular synaptic package manager.
I run Antix stable but I do some testing also for Anticapitalista and friends. Just a joe blow home user though. You can get more answers to your query browsing the Antix forum at
Edit: Forgot to mention that quite a few Mepis users also use AntiX also. And Mepis motto is "It just Works"