I have had several different brands and found them all to be accurate. But if you read the manufacturers booklet on them, if you get say an 800 it is only accurate to +/- 1 yd out to about 400 yds. then the accuracy falls off a little. It also makes a difference with weather ie rain etc.. plus the target that you are ranging. But especially out west, when I hunted antelope a couple of years ago it was helpful. It is also helpful in bowhunting since you can sit in your stand and range different trees etc... without having to pace things off or measure.
Oh, I know the ones that I had were accurate because I would range a target, for archery , and then shoot it for that distance and the arrow would go right where it was supposed to. I also know they were accurate for longer distance because of doing the same thing, out to 300 yds, with my rifles. Also in having several different rangefinders and ranging the same target with all of them and getting the same distances.
Long