From my perspective, I would call the vitality of the two forums to be about equal. Each has roughly the same number of regulars. Posting rates are about equal, perhaps a bit higher here with the ALTs and the shoutbox raping.
Without access to the admin panel, it's tough to be 100% confident of who are alts and who aren't; it'd take looking at IPs to do that. But if I had to guess? I'd say you already got most of the people I personally suspected.
Personally, I'd suspect that DiLF is somebody's alt, possibly Weeg's, but without access to IP data, I can't honestly say I'm 100% confident. It could just as easily be that one apes the other one's posting style.