You want to have the correct gear "looking ahead"; just give the paddle a couple of flaps and go. I use it on occasions for passing, when I want to play, and when I want to control downhill speed without using the brakes all the time. I have no idea how the PlusSix is set up but on the Jag I have it set so that if I use the paddles in drive it goes manual, by holding + for about 3 seconds it changes back to auto, and if I haven't used the paddles for several minutes it goes back to auto. Of course I can always turn the selector to Sport Mode and then it is fixed in manual.
It takes a bit of getting used to the paddles and it would probably be easier with a stick "Sportmatic" system, a sort of clutchless manual.