I know date last posted to is a horrible way to get numbers, but it's also a pretty easy way.
In 2012, across the three boards, 42 pages of threads had a date last posted of February.
In 2013, across the three boards, 40 pages of threads had a date last posted of February.
So the activity, going by the date a thread was last posted to, is pretty close. I think the content has shifted away from an informational exchange to a place people come to complain and correct others, but that's across FT and any board as they keep growing over years. Because there are more of the complaint type of threads, there's less of the informational ones, and it seems like there is less content.
The how much is about the same from last February, the what is probably much less.
To the obsessive self proclaimed fact checkers who have nothing to add to a thread then verifying and correcting things like page counts, remember to set your number of displayed threads to the same setting mine is in my profile, or you will get a different page count.