We don't need no stinken glass.... (for less then 600 yards)
Some of the best 3-gun shooters I know shoot iron sights. Unfortunately, some of us do not have eyeballs conducive to focusing on the front sight. And the highpower setup of reduced aperture and narrow front sight aid in HP, but are slow for 3-gun, especially in the odd positions we shoot from sometimes. So, a low power optic is very helpful. And the dual-optic arrangement works for others.
The Dovetail Angle Mount
is an example of what I was thinking about. And here is the Larue example
but it requires a Docter or J-point. And the Matt Burkett offset mount