Currently Factorio's highest rated reviews erroneously claim that there's "DRM", as one needs to register on the dev-site to get even faster updates.

Is GOG's version always up to date? No, it can lag behind.
(I don't use Steam, so if you also have the game there, feel free to weigh in!)

However there's nothing stopping you from archiving, restoring and using your downloaded game *without any server checks* whatsoever, whether you got it from GOG or the dev site.

This is a misunderstanding of what DRM is and casts this title in a bad light.

While I appreciate that GOG does *not* interfere with user reviews, when they're spreading misinformation, is there a way to clarify such claims?

EDIT: As it sometimes happens, the GOG version *can* lag behind. This is valid criticism, but calling the dev-site registration DRM is a misnomer.

Just learn to ignore stuff like that, especially here. When someone starts screaming in the forum or reviews about DRM, first consider if the game is important to you. If it is, do a deep sigh, and then prepare for an hour or two of really annoying search until you find what exactly is the issue instead of some incredibly ambiguous useless screamy stuff. In nearly all cases that will then end the issue with "not relevant to any halfway reasonable person".

The core problem of this is of course, if something is truly problematic DRM it's hard to gain any traction on it because it gets drowned out in all the people crying "WOLF!" for the most silly reasons.

Normally, it takes a few days to weeks for a new patch from a standard studio to bubble through to any platform (we are not doing a patch just for one issue, it needs to go through QA first, ...). A bit faster if it's a huge dealbreaker right after a big change.

The updates on their own infrastructure can happen daily in hot phases, sometimes even more than daily in really hot phases. If it's critical problems, it has always been pushed through to GOG & co rather quickly, certainly no worse than what I would get just about anywhere else.
If an inserter sometimes screws up if your factory is processing more than 200,000 iron ore in the time it takes four blue butterflies to fly around the rocket silo then it's great that is fixed timely as well but might not be my most important concern.

And I could have gotten the fix even quicker by making a forum account (which does not spam your email) and linking a key to it. Which also gives me another source where to get a completley DRM-free download of the complete, current version. Which is helpful, for example, if GOG screws up the publishing of the Linux build on Space Age day.

Anyone who does not say "this looks like the best of both worlds" here needs their head examined. Instead we get bunch of people who clearly never bothered to even look at the issue (or are simply malicious) going all screamy. Again.