Strongly oppose moving the Research namespace hosted metrics documentation off Meta. It's s'posed to be broadly accessible. Wikitech is on few peoples' radar. Mediawiki.org is for software documentation. Meta is the central wiki for the movement (however imperfect). - J
I respect the fact that these kinds of distinctions make sense to people who are already familiar with the movement and research / analytics. But to someone relatively new, and to me for the first year at the foundation, those distinctions made zero sense.
I'm not saying it's easy, but I think having documentation in more than one place is an awful experience for newcomers. We'll continue to move things to wikitech and leave nice high level landing pages on the other wikis. Others are welcome to act differently if they so see fit. I know a lot of research stuff is on meta, so maybe in your case it makes sense to standardize on meta and point to it from the other wikis.
You're of course welcome to disagree with me but I'd suggest first trying to come up with examples of newcomers who understand the purpose of our different wikis perfectly right away.