Jarrett
There are potentially several other factors as well, beyond what you've already pointed to yourself.
Panda/Farmer issued in a new era where many old "rules" were tossed by the wayside. Some of these were already questionable, as the seedlings of Panda were planted with last year's May Day update. if any single site in your network saw significant drops but not the others, it might well have been something else that caused it. Given the breadth and severity, this clearly does sound like Panda.
Taking a brief look at some of your content, site structure and duplicate content issues gives me even more confidence that's the cause.
Example 1: Duplicate content severity
I randomly picked one article and searched Google. Found a dozen sites where the same article shows up, including the site that's currently #1 in organic rankings in my result, which is the actual author's own site (Daniel Edward Craig). http://www.google.com/search?q=In+this+post+I+discuss+how+newly+available+reputation+metrics+are+paving+the+way+for+the+integration+of+the+online+reputation+management+and+revenue+m&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
How many sites are in your network where you share the content? So that begs the question - do you intend to find a way to give credit to the original news source for articles shared across sites? That's a big recommendation.
Obviously just this factor alone shouldn't necessarily cause bottoming out. News articles from major wire services routinely spread across the net in massive numbers every day.
Yet it's just one indicator to now consider. Especially when considering other major factors. Like the sheer volume of ads on pages. Too many ads is a big factor now. Amount of content that's unique to each site is a big part of the puzzle. If most of the content is duplicated across all sites, what makes each site uniquely valuable?
I could go on, but those are some high level areas for consideration.