Are you looking at current production guns or at guns overall? With current production guns I see no difference. With old side by sides there might be a slight difference. Part due to age and wear and part due to older design. O/U get the benefit of a perfected design while early doubles used multiple transitional designs as all the bugs were being worked out until they worked nearly perfectly. I figure 90% of side by side guns are pre WWII made and 99% of O/U guns are post WWII made guns. So the O/U get the advantage of all the trigger design improvements over time.
^^ This sums it up; single triggers were originally developed on s/s guns - and it took quite a while and a lot of different designs to sort the 'good from the bad'. I would always have double triggers, but that is a personal preference.
