The default value 1.0 work with no load and is used when the motor is with no load mounted

 

In case you dismount a motor then be careful before you start running the motor if the load factor is more than 1.   Then you should set the value to 1 and then you can power up the motor and make the tests and then adjust the load factor before mounting the motor again.

The MAC motor algorithms are exceptional and the standard filters will provide up to a 250:1 ratio between load and motor inertia.

The load factor should be carefully chosen.  If there is backlash or you use beltdrive you can't go as high than if it's a load directly mounted on the shaft with no backlash.

The standard filters are already tuned pretty hard to allow maximum torque at high speeds. That's why you'll notice some noise from the motor as it adjusts all the time at standstill. This noise is coming from the current loop and can be reduced in non aggressive applications by reducing the KIFX1 parameter. 
This is the only filter parameter that should be adjusted.

Other filters can be supplied for extreme situations but we have found
that the standard ones supplied fulfils 99% of the typical applications.