Just mean to share my perspective as the guy who essentially "forked" INTPcentral into a new forum a while back ... be prepared. It may not be obvious to some ... the amount of effort, time and money that can go into establishing and (key: )maintaining a forum like this.
Also, I was in a position of not having any access to the underlying data or domain of INTPc, back when. So it was a clean slate. At least in our case, that was generally desired or at least acceptable to most. Later, we obtained a sort of archive of the old place, although since there is no formal relationship between our team and the team of INTPc, we don't publicly host it, since it isn't "ours". Cue more politics and effort. Even so, we have our history preserved, without any cooperation of the original management (although that may change in days to come, etc, blah).
In our case, the fork worked because -- to put it diplomatically -- INTPc had been abandoned to all sorts of problems for too long. There was little if any tearing of the culture between two sites.
I write all this with the best of intentions as another guy in the INTPish forum space, to share my particular experience in a "forked" forum situation. In short: it is work, ongoing. Be sure its worth it to you! Have a clear idea of what you want to preserve, what you want to drop or change, etc. Have the money and time set aside. But first, of course, see if you can reconcile your desires with the extant madministration? (and, yes, we tried that before instituting our "fork")
Nevermind all that involved with SEO for a new domain name.