I actually like Fedora’s “core” approach – the fact that they allow you, as the user, to stick with an older core until you’re ready to upgrade. If you go with the philosophy of upgrading to a core that is two generations old or so, you can probably do pretty well with it.

Gentoo has profiles, which are similar. They allow you to specify the architecture, type of machine (eg server|desktop), and release date (there are typically two or three release dates per year). However, that doesn’t keep you from getting newer packages once you’re up and running. For that, gentoo’s portage package manager allows you to specify e.g. that you just want the “system” set of packages updated, and gentoo keeps that set of packages well-maintained and stable.

I take it that by default, Debian keeps you on a slightly older release cycle. Is there a way to specify how old, so you can just get security updates and avoid newer features?

In the end, a linux distro is just like any other software – either it’s actively maintained and has a good QA cycle, or it eventually dies. With all the activity in the linux software space, it’s just amplified.