The latest AC2 code is posted. This is the last code before the big switchover to APM2 codebase.
What you should expect: More stability and better handling, especially if your CG is not centered.
Heres the update list from the downloads section:
Most stable flying version yet. Includes new stability patch by default and a new DCM gain and clamp value that should reduce drift due to linear acceleration in missions or long flights.
Switched rate gain calculation to use raw IMU rather than the DCM's omega. This crisps up the response a lot.
1280 has lost local flash logging, sorry, but it's just not supportable any longer.
some older tests have returned now the program memory is freed.
Remember, to use the new logging format on the 2560, you need to erase it at least once to format it.
He're the video showing just the control loop patch. The DCM patch was added later and improved the handling some more.