HI ALL i have had my dct ct since Christmas and have rode in all weather and road types so i have played with all gear options so lets make this easy:
D Mode....... in d mode the bike acts like an automatic car in the way it changes gears, like when you accelerate it changes gear, when needed to continue with the speed gain and when you throttle off it will only gear down when the speed and revs match its program to stop it chugging in a high gear and low speed and will only gear down as you slow. this means that if you accelerate to 40mph and throttle off it will stay in eg: 5th gear until you speed drops to the best speed for 4th gear and the it will step down and so on to 3rd , 2nd, 1st.
if you brake it will obviously gear down quicker to match the rapidly slowing speed.
S Mode..... in s mode the bike will act like d mode gearing up and down but it will rev higher and change down later so as to keep you in the right gear to pull away. best example off roads on race track is, red line acceleration 1,2,3,4,5 throttle off for corner it drops one gear to 4th or two gears to 3rd to give you the best acceleration, from throttle back on with high revs or red line if you have twisted enough. (IT BEHAVES LIKE A RACE BOX) (AND IT THINKS WHAT YOU ARE DOING ON LEAN ANGLE AND THROTTLE SO AS TO GIVE YOU POWER INSTANT) so i am told....
manual this is the good one it will not change up in any gear to the next until you press the gear up. it will change down like D mode when you slow or stop. it is incredibly difficult to stall even like me throwing to on the floor twice the engine only stops on the lean angle sensor been parallel to the floor so i figured out.
In manual you can bounce off the rev limiter and when creeping through traffic i go manual 1st gear so as it wont change up if i get too quick.
in both D and S the bike makes sure you are in the right gear for wanting to accelerate in manual it does but wont gear up to keep you accelerating, it redlines and bounces lol
if this does not give the answer pm me or ask and i will delve deeper