Bio I'm a Resident Evil collector specialising in Japanese books containing hard-to-find interviews and extra story notes not in the games. I'm also a fan of classic '80s horror franchises such as Friday the 13th and Halloween.
Lot of business (I've worked on all three as an admin).
Long story short, Halo Nation suffered a lot of problems with writing quality due to most editors not wanting to associate themselves with 343i's lore and not collecting comics; novels, etc, but it still had tens of thousands of readers per day. Halopedia meanwhile is where the comic/novel collectors go, so they're up to date with lore, but have fewer editors since Halo Nation has the higher position in Google searches.
A number of Halo Nation editors forced in a "vote" on whether or not to move as a group to Halopedia, thereby boosting the number of editors it has there. This was a show of defiance against Wikia, owing to the installation of a Video feature which could not be removed, and the content of which derided as inaccurate (which casual readers would assume was the admins being idiots). Similar complaints were raised on other wikis. Wikia offered for Halo Nation to proof-read Wikia videos to avoid errors, but the other admins were unwilling to go with that.
I was opposed to the whole thing owing to bullshit we went through in the initial Halopedia/Halo Nation split, but it seems a lot of people actually give enough of a shit about a video they can pause that they'd rather go to a different site.
If you mean what's going on right now (just realised)? The current plan is for Halo Nation and Halopedia content to share a single website, and readers get the option of whether to read articles in the HN or HP skin. I don't really get how it'll work, though, since there's no way having two versions of 9000 pages is going to work on a wiki.
"Battlestar Wiki" is well known in the fandom, and was closed down after a few years of inactivity when it could no longer meet server costs ("clone" is an archive of it, which can't be edited). That said, there's more than enough ex-Battlestar Wiki editors that copy-pasting its content WILL get attention. Looking back as late as last year, this wiki got complaints from their staff over it.