Why has the smoothing option been removed from IMU04?

Essentially, this has been done because the hardware within an IMU04 is totally different to the IMU01, IMU02, and IMU03.
 

The IMU01, 02 and 03 have no form of signal conditioning or intelligent internal filtering, and is restricted to a sensor sample rate of 100 Hz. For these reasons, the RAW output inherently more susceptible to noise. In order to reduce this noise, we implemented a simple smoothing setting within the configuration software – while this was effective, it did have an impact on the accuracy of the IMU data.
 

The IMU04’s internal gyroscopes and accelerometers have a higher accuracy, with a sensor sample rate of 2 kHz. The RAW sensor information is then conditioned, filtered and temperature compensated at 400 Hz. The filtered/conditioned signals are then output, and do not suffer with the same noise as the older IMU units.
 

For the reasons explained, we have removed the smoothing option from the software when connected to an IMU04. If smoothing was applied, it would have a significant impact on the accuracy and latency of the IMU04.