I’ve started working on the flying thing again, and I almost have the flight software to the point where I’m happy with it. It still needs a little tweaking, but in general it’s much more stable than it’s ever been, and it’s still very agile.
I ditched the Kalman filter and went back to basics, using simple integer math and a single 3-axis gyro. It won’t auto-level itself, but it’ll stay where I put it remarkably well, and that’s all I really wanted. Check out the video of my first crash: