One thing I've noticed is it looks like the site, at least the OT where I stay most of the time, has stopped growing. Look at the majority of the threads and you will see mostly people who have been here 2+ years with rather high post counts. Very little, if any, new blood coming in.
Plenty of new blood coming in -- thank the SECr. Whether it's needed
blood is another question.
The big difference in the OT from when I signed up over 5 years ago until now is that back then the board was totally dominated by one group, the frat pack-Tier 1 clique who all seem to know each other IRL (that was one of the things that most struck me about the OT [that and Slo's then-mind-boggling 67K post count -- how quaint]; I'd never been on a forum where so many people were IRL friends). They are no longer anywhere near as OT-dominant as they used to be. As I've written before, the very existence of a Tier 1 thread is acknowledgement of their influence receding.