I am also not a 3 dot sight fan for a few reasons:
1) The dots and the tops of the sights usually dom not agree.
As someone noted above the aligning the dots often means the top of the front and rear sights are not aligned. That creates different points of impacts if you shoot precisely using proper sight alignment versus the allegedly faster sight picture offered by the 3 dot sight.
Part of the problem is that all three of the dots are usually the same size, but since the front sight is farther away the apparent diameter of the dot on the front sight is now smaller. Sight makers don't seem to account for this issue.
2) Three dot sights are less precise.
Under ideal conditions of light and contrast the Mk 1 Mod 0 human eyeball can detect differences of .005", and a good pair of sights will create those high contrast conditions. Handgun sights tend to have slightly larger gaps than are ideal, but they are still capable of a fair amount of precision, and all black sights will consistently be more accurate than 3 dot sights.
In short, the spaces between the dots are too large for precise alignment, and the round shape of the dots makes precise alignment much harder, and much less consistent across different light conditions.
In addition, you now have 3 dots competing for attention with the light coming through the spaces between the front and rear sights. The fact that the dots and tops of the sights may not be consistent just aggravates the problem.
3) Three dot sights are not any faster. If you are properly trained and practice enough you'll find that referencing the front sight blade only is both faster and more accurate when shooting fast. You have to start out slow and develop both a consistent grip that allows you to align the sights as well as consistent trigger control that allows you to maintain that alignment.
In essence, you bring the pistol up to eye level and then as the front sight comes on to the target, you pause to verify the front and rear sights are aligned, then proceed with the trigger squeeze.
Over time, you develop both a consistent grip, and an eye-motor loop that ensures that the sights will always be aligned as you bring the front sight on target. Your brain knows exactly how the muscles in your hand have to be tensioned to achieve sight alignment and at that point sight alignment takes care of itself, for all but the most precise long range shooting. Once you reach that point the "pause" to verify sight alignment can be less than 1/10th of a second and serves mostly to confirm the front sight blade is on the spot you want to shoot.
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In terms of sight picture, I use a 6 o clock hold on the target for precision shooting, but I place the front blade over the target for short range, high speed shooting.
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I do use 3 dot night sights as at night aligning the three dots is as good as it is going to get.
However, I cover the 3 tritium dots with a black sharpie. That gives me a standard black on black sight in daylight, but the tritium dots will still show through the thin layer of ink in the dark, giving me a 3 dot sight at night.
