The Rev 2.2 IMU boards are being assembled by lots of folks and many of them have reported successful assemblies. I'm glad to hear that everyone has had such good luck so far.
Aaron Kahn wrote a six state Kalman filter AHRS that tracks gyro bias. We've found that the Toking CG-16D gyros have significant drift and temperature sensitivity, so this extra state is required. Full source code is available in sim/src/imu-filter/ahrs.cpp.
The code works great and tracked twelve hours of data with no problems. It runs at 62 KHz on my P4 and 70 Hz on my iPAQ. We'll be running with the iPAQ on the helicopter, so this is fast enough for realtime sensing. There is no FPU in the SA1110, so it is an enormous difference in speed between it and a desktop CPU.