I was wondering if it is necessary to be at a full stop in order to shift from D to S, vice versa. I'm asking because when in the mountains, I'd rather use sequential mode to use engine braking and reduce the amount of time I'm on the brakes.
Correct. No need to be motionless when switching back and forth. I commute "over the hill" every day also and rely on the faux-manual mode when descending. But, I sure wish it had a 3.5 gear. The car 'runs away' too much in 4th and 3rd has too much compression. I usually use 3rd with a very light pedal, (acceleration pedal that is, not the brake pedal).