Okay, I'm no pmdev
, or anything of the sort, and I can't even begin imagine how much the fine folks here have hacked Everything Engine. However, I have Everything installed and am using it for my personal site.
From my experience with this, I can tell you that the 'base' for just about everything on perlmonks( chatterbox, threading system, voting ), is available for your everyday, run-of-the-mill Everything system. The beauty of it is that everything on Everything is hackable, leaving it wide open for development like perlmonks, everything2, etc.
So, to answer your question, I'd say that the Everything code running perlmonks, is good for perlmonks, but probably nothing like Everything. :)
A conclusion is simply the place where someone got tired of thinking.