Bearing in mind that the difference in elevation is under 1 degree at 100yds and less the greater the range.I think sticks will give you a safer backstop more often, given higher elevation than when laying down. I'd also think that there is less visible movement involved in setting up quad sticks than taking off a backpack and laying down with it. Sticks are handy too for steadying your binos when scanning on a stalk.
But as everyone has said, it's going to depend on your ground. I haven't seen may people using sticks in the highlands.