I have a 2018. Unless I am in a real hurry, I just leave it in D. My fuel economy is definitely better that way. If I am in a more aggressive mood I'll use S1 or S3. If a lot of twisty turns and I'm riding aggressively I go with the manual mode. So about 80-90% of my riding ends up being in just plan ol' D.
I have noticed it is fairly responsive to down shifts when in D but it seems to be more of a function of how quickly I twist the throttle and/or if WOT. The DCT is what prompted me to buy the AT anyway and so far I am very happy with it. I have a 1260 Multistrada and a S1000XR ADV bikes and I have maybe only put 500 miles on them since buying my AT AS. That is a good indicator of how much I just enjoy riding the AT.