Might I suggest looking into who it is at M-Tier that's producing these packages? It's not just some random third-party.
FWIW, the openup tool makes things extremely easy and it certainly doesn't "involves lots of time". Run "openup -c" from a cronjob and, when you get an e-mail saying there are updates available, log in and run "openup". Kick off a reboot if the kernel/base was updated and you're good.
I run several OpenBSD boxes in production. Don't let this be what stops you.