I use a FFII on my Beretta Neos, but I also put it on a Sig 556 for a while. A little over 1 MOA at 100 yards.
Very bright dot, good battery life.
Dot is non-adjustable for light conditions. Can be a bit obnoxious getting it zeroed. Sometimes the locking screws move the dot, sometimes they don't. Once they are tight, the seem to hold indefinitely.
If you use one, I recommend Loktite for the mounting screws. It did fine on my Sig, but that little Neos hammered them so bad I literally could not zero the sight in because the mount lug and the battery screws kept backing off.