At lower levels, within a forum/section, the first part of the sell has already been achieved and the user is now within the site and interacting with it. The sales pitch is virtually over... the key bit now is customer retention.
I agreed with everything you said before this, but I don't agree with this statement.
For the very simple reason that is you are remaining true to your stated (defining) purpose of providing an independant sub-forum (or section, or microcosm, whichever you like to call it) experience, where each sub-forum is almost responsible for making its own rules, admitting its own members according to its own criteria, and having its own unique members and topics, then definitely you need to promote the same big (vanity) numbers for each sub-forum too. They each in their own right need help with their own promotion and publicity.
That's where the stats on each sub-form meta-bar is as valuable (to that sub-forum) as the big stats on the main forum meta bar.
Another way to look at is like this: the main (parent) forum can be almost rendered completely insignificant, because people don't go to it for the sake of it, they go there because they have to. To find the sub-forum that they really want to engage with, the rest can go and take a jump as far as they are concerned. The main forum is only a mask, the sub-forum is where all the action happens at the localised level, the whole purpose I thought you had for "microcosms"?
At the end of the day, regardless of how we differ in our opinions, how hard is it technically to implement this meta bar statistical reporting feature at a sub-forum level anyway? Are we just splitting hairs here when it comes to technicalities?
Some people would like it (and confirm my position) and others wouldn't care if they were there or not (confirming your position). You can't please everyone all the time. But what you are doing is being faithful and true to one of the main differential feature from other social community sites: the lowest level autonomous community. If so, then treat as though they deserve to know their own stats too.
I appreciate your thoughts David.