Watch out for what packages you rely on, and what repository those packages come from. If they're in universe, expect your bug reports on Launchpad to go unanswered or unresolved. The only way to get fixes in them is to go upstream to Debian. But note that not every bug in a universe package is actually fixable or broken in a Debian world, because the bug might be down to interactions between a decision made by Canonical with packages in the main repository, and those for the universe package.
Ubuntu is currently divided into four components: main, restricted, universe and multiverse. All binary packages in main and restricted are supported by the Ubuntu Security team for the life of an Ubuntu release, while binary packages in universe and multiverse are supported by the Ubuntu community.
https://wiki.ubuntu.com/SecurityTeam/FAQ
If you care about security, disable universe and multiverse on servers, or use Debian Stable if you want a Debian-based distribution.
The closest counterpart is SUSE's PackageHub, which is often seeded by stuff going into openSUSE Leap that isn't part of SLE itself.
I would love it if Red Hat were to give it proper recognition. I honestly don't know why they haven't yet...
Ubuntu specifically has a "server" version. I've been using it since 10.04 (almost 9 years) and never had to use anything else.