I found this interesting article that might explain a few things. Also, I found that depending on the size of the tractor and loader, the FEL could hurt or not. For instance, the very small tractors already have a very low COG.
Tractor Fatalities According to the National Institute for Occupational Safety and Health (NIOSH), about 250 people are killed each year in tractor accidents. Rollovers account for more than half of these fatalities, despite decades of effort by tractor manufacturers and farm safety professionals to
nasdonline.org