My EM7180 does use the accelerometer and the magnetometer to correct the gyro and is using some variant of a madgwick filter (as far as I can tell). It has a configurable parameter to control accelerometer latency that is used to "mask shocks for more accurate inertial navigation". I have that parameter set, but not sure if that is helping or not. I've done about 18-20 flights with the EM7180 (>10K') and have never seen any anomalies, drift, or errors with my tilt values coming from the quaternion output. I've got a lot of raw data and onboard video to confirm.Not necessarily on tilt. If the IM7180 is using the gravity reference vector to correct gyro drift (as most IMU chips do by default) then you can have an indeterminate error on the tilt reading.
Would the gravity reference be more of an issue if I exceeded the 16g limit on the accelerometer?