Here's what I did to get upgraded to debian unstable, and it all went without any problems of any kind....which is lucky because I just blundered in without reading any docs or threads as I was just playing around having cloned my previous Zenwalk install in case I wanted to switch back easily.
Installed Antix m7 latest version
apt-get update && apt-get upgrade with default sources.list unchanged
added extra apps/DE as required
enabled all repos and added debian unstable deb and src
apt-get update && apt-get dist-upgrade
(everything went smoothly, the first apt-get upgrade had taken care of almost everything)
Then commented out all repos except the unstable ones.
I now have Antix running Debian Unstable and had no conflicts or dependency errors along the way. I had one lock up of X yesterday while playing a 3D game (cube) but I found the same on some other distros using the latest X so I believe this is a X server /new intel driver issue rather than any problem with Antix in particular and I'll probably try to go back to a testing version of X and intel driver. I'm incredibly impressed with Antix and its speed and low resource use. I've added a few extras like wicd for easy wireless connectivity on my laptop and I've also installed Xfce so I can easily switch between fluxbox and something a little more familiar/shiny for anyone else who uses my machine. Xfce is also extremely fast on this set up, barely needing any more RAM to boot than fluxbox....and massively less than Xubuntu or Zenwalk 5.0. This has been a real eye opener for me. My 3 or 4 year old 1.6GHz Centrino laptop (Asus M5N) has become a seriously fast computer
with cpu freq scaling, proper power management, perfect suspend to RAM (even reconnects to wireless on unsuspend) and every application I could ever need. Wow! Anticapitalista I think you really hit the sweet spot with the default set up.