If my Xterra got rear ended, the bikes would be the least of my worries!

Then again, your bikes probably cost more than mine!
I have used this rack for more than 20,000 miles. Hauled bikes across the country. Same rack, another vehicle, lake Yellowstone in the background (frozen).
I usually put bungy cords on each bike, and the way the cradle is designed, each bike is held apart, so the only things touching are the tires.