There are several downsides to rangefinders. The first is the magnification. You can't range a reasonable sized object at 1000yds with 4X. Even a car door sized object at 400yds with 4X is somewhat hard. Especially with the thicker crosshairs some of them have.
Holding it steady,on the object,while you hit the button is another problem for getting the range of smaller objects,even at the reasonable distances. You can't range what you can't zap with the laser.
Getting accurate distances with a rangefinder is easier if you "pre-range". Zap the rocks,trees,hill sides,etc,in your hunting area. But of course this does not help if you are hunting pronghorn in Arizona. You sneek over a ridge,see an animal,and have to zap him. He has other animals with him and all of them are moving around.
Another problem that I quickly found is the stated range is never quite true. A rangefinder that states it is good to 800yds,might be good to 500. The 1000yd rangefinders that you pay bigger bucks for,are only useful out to 600-700yds.
Picking a rangefinder,balance the stated distance,with the type crosshair,with your TRUE usage. Bowhunting deer is one thing,hunting Big Horn ram on the side of a mountain is altogether different. --- SAWMAN