We have to do high lift certification on a yearly basis.
The reason they want you wearing a harness is that if you flip the lift, you dont get sling shotted (?) out....
they want to find you as close to the crash site as possible....
Its really for the "I can reach this...." syndrome. I have seen guys tumble out at 140' trying to drive that "last fastener".
Most importantly, watch out for soft ground and power lines....if you see a flash, dont smile, they are NOT taking your picture.