I have four NiteGuards - one on each side of the coop/run. I live in the woods and so far have seen no sign of any type of predator around. But I have only had the girls outside since July. And I have built Fort Knox.
I have been using the Nite Guard units (3 of them) and had NO problem - yet! - with known raccoon predation before I set 'em up. Raccoons got all of my Koi, most of my goldfish, and tore the pond plants up on a nightly basis. I set up the Nite Guard units, and WHAM! not even any wet paw print marks on the pond restraining walls. I got three of them because the fourth side of the Chicken Compound is within 15 feet of my house, and I rather hoped I could save some money, hoping the proximity of the house would help combat night-time critters.
Oh, I've used these for about 9 months. Really remarkable.
Just saw the Bright Eyes unit the other day and thought, hmmmmmm.... less expensive, and TWO red lights, maybe I could pick up a couple of those and test them side by side, so to speak, for comparison??