Bit off-topic but related to discussion on stability and control of transport aircraft - have recently seen presentations and videos related to recent research between NASA and University of Illinois.
A pretty impressive remote control model:-
The remotely-piloted Airborne Subscale Transport Aircraft Research (AirSTAR) generic transport model
NASA AirSTAR Testbed - YouTube
Nasa - AirSTAR (HD) - YouTube
and safe way of testing approach to stall and recovery
Video highlighting testing of an L1 adaptive controller developed by the University of Illinois and University of Connecticut flying on NASA's airborne subscale transport aircraft research testbed (AirSTAR) testbed during a 3-day flight test campaign at Fort Pickett in Blackstone, Virginia from 2-4 June, 2010.
The video shows how the L1 controller makes the aircraft controllable through a mormally divergent roll oscillation and a post-stall region.
AirSTAR was developed in part to help define and augment the control properties of large transport type aircraft in unusual attitudes or post-stall orientations, upsets that have led to numerous loss-of-control accidents, but which are not tested on real aircraft for the obvious safety reasons.
NASA AirSTAR full stall with subscale large transport - YouTube
NASA AirSTAR testing L1 adaptive control for post-stall control - YouTube
In none of the tests I have seen was there a stable post stall, but maybe due to scale it was just beyond the ability of the auto controls/remote pilot?