While I like the ACOG (I have one on my
M&P15), I don't like the piggy back RMR. I've worked with my buddy to get his sighted in. The abnormally high offset from the bore makes for some interesting hold overs (and unders). I tried to give his an honest evaluation during some serious range drills and simply couldn't find anything I liked about it....and more so....there was nothing he could do with it that I could not do equally well, if not better, with mine. At the training courses where I've used mine, course of fire was close contact out to 400 yds, including hostage taker headshots at 5~7 yds. The ACOG, by itself, managed all of it just fine. FWIW, save your money and skip the RMR option.