I tried variable switching frequency (Parameter 412) this morning but it works the opposite to what I was hoping. It does sound cool though!
It increases frequency with RPM as per the manual. I wanted a low frequency at low RPM.
Low switching frequency (Parameter 411) seems to be the key to prevent lurching and brief rear wheel lock up when decelerating to a stop. I could also try raising the stop frequency (Parameter 123) but I didn’t like this set higher than 0.