The Grumpy Editor's guide to (some) development distributions

Speaking of Gentoo:
Gentoo is suitable for stabel systems as well as being on the edge of development. I use it on
critical servers as well as on developing systems.

Gentoo has "emerged": using the live  and install cd you can easily get up to a running system
without compiling. This is your starting point.

the package management is done by a tool called portage and this tool has some advantages: you
can decide implicitely or explicitly for wich packages you want "stable" or "development"
conditions by using package masks. You can even select the versions to use / not to use in
fine granularity. if you want to update a package, you can take a snapshot of the old version
and then upgrade, leaving you a backdoor if something goes wrong.

gentoo provides a tool to do check your installation for security related updates and perform
this automatically.

Another advantage if you are a frequently-upgrading person is that gentoo leaves your config
files untouched and provides tools to do the merge process. this saves some anoyances after
upgrading.

if the update works, you can build a package and update other similary configured computers
from this.

Gentoo has drawbacks, too:
Config options are poorly documented, you need to search the forum for information. There are
no fully functional shiny gui tools for doing updates.
Compiling from source needs some patience. To get the X desktop as functional as in ubuntu you
need to manually select apropriate software and configure it to work correctly - without
documentation.

But if you want to be on the edge, this may not be a showstopper for you.