Is the Z gyro being used for any purpose? If not, maybe it can help to improve altitude hold and stability.
Well, it is the reason we have 6DOF right? The recent addition of using the Accel Z is a good move.
It's experimental, but it works for many people. You need to enable it in the APM_Config. Look at the bottom of attitude.pde with a code editor to play around with it.
I think the MPU6000 will be much more noise resistant and make this feature more feasible.
Thanks Jason, you mean both Accel and Gyro Z are being used?