A "Red Dot" is a loosely used term to describe a reflex optic sight (easier to say too). The indicator can be a dot or a triangle (or something else) but they typically are both called "dots". The MOA indicates the size of the indicator in "minutes of angle", a MOA is 1" at 100 yards. The smaller indicator is typically more precise due to it's smaller size on the target, this is good for distant small targets where you have a lot of time for each shot, but when you get close in and have to move from target to target quickly, the small dot is slower to "pick up" for the next shot. I use the larger dot (or triangle on the DP) as do most of the USPSA, 3 gun, and Steel Challenge Open pistol shooters. If you're going to standing at a range shooting targets in your lane, then the smaller indicator is probably better, but if you're going to be shooting action pistol, outdoors, at multiple targets while on the move, the larger indicator is (IMO) it faster. (and easier to see in the sun).
