VinDSL said: Heh! I aimed to do this, but was afraid to pull the trigger. :D
Maybe I'll try it, before I install Alpha 1, just to see what happens. It is a very bad idea to mix the repos for Ubuntu and Debian.
There are many packages that you can get away with it on but Ubuntu changes some of the paths and some of the files all together. This is probably to improve speed or to make things compatible with other packages that they use.
Just as an example all of your (or most anyway) images used in Ubuntu are in /usr/share/backgrounds. Most in Debian are in /usr/share/images/desktop-base. These are just images. Little changes like that in a system file and you have some major problems.
There are also things like the package name itself. If you have a call for a package from somewhere in Ubuntu and you have replaced that with a package from Debian with a slightly different name there will be a problem even if the packages are identical which is not certain at all.
If you have more than one box it is interesting to look at these things in Synaptic. My wifes laptop runs 10.04. I have an install of Squeeze. These are about as close as you can get to a match. There are some fairly major differences in key areas between them.
Here on this forum, having to do with ralink cards, ronacc points out that there is no "firmware-linux-nonfree" package in Ubuntu and that he can get the same fail in Debian by installing that package there. As he points out this is probably due to Ubuntu incorporating that firmware in the kernel.
You could probably install grub from one to the other. If you put the Debian grub on Ubuntu you are going to have problems getting your menu background to work as Debian has edited the files so that the only place grub looks for that image is still in /usr/share/images/desktop-base. Can't recall what the image name that it called for is as I have changed that in all my installs.
But, as you can see, a whole sale dumping of Debian packages onto Ubuntu, or the reverse, is going to cause a broken system that will probably require a reinstall to fix.
I find it interesting that Kanotix Hellfire, based on Debian, uses the Ubuntu kernel (recompiled) and Wine 1.3.19 (per Lucid PPA). They must be very careful, as must the Ubuntu devs, in this mixing. One package wrong and the whole thing may collapse.
I was just over on my transplanted Lounge Lizard install that went from Ubuntu 11.10 to Debian Sid. It works great. The home directory is set up the same. I removed (saved some in another folder) all ~/.whatever files from the /home partition. Installed Debian on the / partition with format and the /home partition without formatting. That way I avoided the problem of mixing repos.
I would not install more than one at a time from that repo and be very careful what I picked. Not sure I have the guts to risk an install like that at all.