in building up my fixed gear conversion i used moutain bike spd pedals and ive had no problems getting used to them.. a couple 0 mph falls here and there but mostly the first time i tried them.. the last fall was a freak accident in which my cleat got caught in a pedal as i was cruising up to my apartment door.
i say just dive in, take a few hours to adjust and itll be fine..
i can't imagine riding fixed with anything else