I am going to assume that you have "Configurable Dynamics" (I don't). After all of the research I've done, it only becomes more confusing. Dynamic mode causes the transmission to shift faster while Sport mode causes the transmission to hold gears longer for those who enjoy using the paddles.. Makes sense, right?
Configurable Dynamic mode allows you to make individual settings regarding shift points, suspension, steering weight.
This may be one of those times where you just have to experiment with the settings in order to compliment your driving style and the roads you most often travel.