I'm gun shy due to previous bad experiences with APT and when I worked for a Linux distro maker it was an RPM based distro.
I would take Ubuntu on a preinstall ...
Odd. I switched off of RedHat after the third time that up2date hosed by RPM database.
Here's the basic difference in how the list of what's installed on your system is handled by the dpkg-based distros and the rpm-based distros.
With the dpkg-based distros there is a text file in /var/lib/dpkg/info for every package you install. When you install a new package a new file is added in that directory. The file has a list of what files were installed on your system and other configuration information. So when you query dpkg about what you have installed the utility looks in the directory and then reports back to you.
On rpm-based systems all of this info is kept in a Berkeley v4.x database. If something crashes while rpm or up2date or rhn is accessing that database you can lose the database. At that point you can't tell what packages you've installed or what needs to be updated. Unless you have a good backup of the database you're screwed.