I wouldn't put a red dot on my defense pistols for one reason.
At this point I don't have the muscle memory to have the sight lined up immediately on draw. Playing with red dots I have to "find" the dot. Takes me longer to do that than it does to get the sights lined up because there's not much reference.
Red dots can allow a shooter to shoot very accurately with a pistol. The main limiting factor with the red dot itself is the MOA size of the dot as well as the shape..