I definitely freak out the first time I coast on a freewheeled bike after "coasting" (not resisting or pedaling) on the fixed for a few weeks. Then I remember I have brakes.
It has improved my timing/flow more than anything, whether in traffic or on the trail. I don't know so much about my cadence/power, I always feel really weak on my other bike--2.35" knobby tires vs. 23c slicks will do that.