I use a 3 moa dot on a Burris Fast Fire 3, and the dot is good and crisp. I also have had cataract surgery so my vision at distance is quite good.
But here is how I get the holdover right. The B-8C timed fire bullseye target has the perfect size circle black bullseye to use as an aimpoint for the 3 moa dot at 100 yards. So I put a clean fresh target near the top of the target frame and go back to the table and fire off five rounds, very carefully. Then I go back to the target and see where the group is. In this case, the group was something like 18" below the aim point. Then I put up a fresh target with the bullseye covering the first group, turn on the cameras and go back and shoot a group. If nothing has changed, the new group will hit exactly in the center of the targeted bullseye, stapled below the aim point. This way, I don't have to change the zero on the sight from my standing, single hand 25 yard bullseye match zero. I never touch the sight adjustments. I will hold for wind but, on a very gusty day, I'm not going to attempt this anyway.
Joe