I had a cheapie Adco years ago. I used it on a Maverick with a 14" J&J straight rifled brass barrel...probably the most accurate & consistent marker setup I ever shot. With even half-decent paint, it could hit a pie plate (about 9" diameter) 9 times out of 10 at 100', so when I had time to line up a shot, the sight was extremely effective. Unfortunately, since I was usually the only pump shooter in a walk-on group of semis, I rarely had that time.
I later sold off the Maverick (one of my dumbest moves ever) and bought a Phantom. I tried the same sight on that, but with the SC feed on there, I never bothered to properly zero it in, found that I never used it and threw it in a box somewhere. Now I pretty much just sight down the top of the barrel on my right-feed guns and down the side of the barrel on my SC or center feed guns. When my KP2 comes back from Palmers, I think I'm going to get a decent red-dot for it, for intimidation factor if nothing else