Updating to more current systemd releases is, generally, safe. However,
we're going through a ton of transitions right now, including the cgroups
refactor, the move to systemd-bus (to prep for the kdbus move), and network
management. While none of these explicitly break backward compatibility,
they have introduced temporary stability issues. I'd worry about tracking
upstream too closely for a server OS. Also, RHEL will have to have some
answer for this, too.