Read a really interesting article last night where they compared shooting with a peep sight, regular non-lluminated scope and a red-dot closer range type scope...the red dot won and by a substantial margin..the brain gravitates to the red dot and object its on readily per the article..
While I don't have a scope on a double..if I were to do so it would be a red-dot such as a Aim-point or trijicon of some sort..