Since I always, always, ALWAYS forget, I'm kind of against it.
My whole family was so consistent about forgetting it that the local priest would come back to the church an hour later on "THAT Sunday" to watch us get out of our car in an empty larking lot and watch the realization dawn on our faces.
Whether or not it saves energy, I loved the cartoon that showed a mother with three klids in one bed with a short blanket. She had just cut 4" off the top of the blanket and sewn them back on the bottom of the blanket.