Definitely stable + backports. Testing is your worse call because you don't have all the updated stuff of unstable, and security updates must go through stable backporting -> unstable -> testing.
I didn't say debconf was not scriptable. It is. You can configure it to show you only ubber-critical things that it must ask, and even then there are reasonable defaults. Your debconf answers are saved by default.
Well, what you say regarding Debian is true, but the Debian policies (IMHO) are what make the difference. Take the menu system for example. It's not enough that it's there unless every package of a graphical application is required to register itself with the menu system, so that you have a consistent menu of applications regardless of desktop environment/window manager you choose to use.
Red Hat and Mandrake have adopted Debian's menu and alternatives systems, but their packages don't use it very much (yet). There are only a few alternatives options on a Red Hat 9 install I did yesterday.
With fat clients and keeping your central file system replicated to client machines, you might want to look at an rsync solution. There is probably something on freshmeat for doing that.
-Roberto
