Here is a very interesting empirical paper examining post-Twombly pleading from Martin Redish and Lee Epstein describing the state of affairs at the appellate court level, they write:
To briefly summarize the state of the appellate doctrine on the issue: (1) two circuits (the D.C. and Federal Circuits) have concluded that Twombly has changed the pleading standard not at all.88 (2) Three circuits (the Third, Seventh and Tenth Circuits) view Twombly as establishing a sliding scale standard, tying the level of particularity required to a projection of the amount of discovery to be involved.89 (3) Five circuits (the First, Second, Fourth, Fifth, Sixth, and Eleventh) construe Twombly as establishing some form of a heightened pleading standard.
At the district court level, the authors examine decisions in the First and Fifth circuits and find that Twombly has not been limited to antitrust decisions or to otherwise complex disputes. Even more interesting, the authors find that “in nearly 40 percent of their decisions in 2007, the judges eschewed Twombly for Conley.” Read that last sentence again.