I don't use them on my quad, i don't like how the front end plows in to the sand if you slam in them.To each his own. In the dirt i use them but rarely.
That's one of the best things about front brakes in the sand.
Regular traction concepts go out the window in the sand.
When you plow the front tires in the sand, you get a lot more stopping ability because you're pushing all of that sand forward and apart.
At times when you really need to stop, it's a life saver.
Going down a steep dune, the rear brakes can lock the tires up and not even slow you down...but light braking on the front slows you down easily.
Rear brakes alone in the dunes remind me of when I was a kid with friends trying to beat the record skid mark on a bicycle.
Lock the rear tire up and you can skid forever with the right amount of weight distribution and speed...it's almost like you're not even using a brake to begin with.