Nice bit of research.
I will vouch that the registration dates are mostly off. I had originally signed up in 2002 - when the boards were PHPnuke (I believe, I could be wrong - didn't pay attention then) and that data didn't migrate over if at all.
Also, I didn't come to UHall until 2013 when I became staff again, most of my forum action was on the Napa shard. I avoided UHall lake the plague!
There are many that will not come into UHall simply because of the bad rap its had over the years. Its gotten "more gentle" over the past 4 - 5 years though, so is not all that bad, kinda like the UHall crowd now.
There is a lot of traffic over on the Trade boards.
BUT...
Stratics is not just about the Forum. There is a whole lot of content over in the WordPress and the PHP pages that gets a whole helluva lot of traffic! Too bad the displayed analytics don't show that.