One-pipe Radiator Valves...

Is it possible to use a motorized, two-stage (ie. fully open or fully closed) valve as the shut off on a steam radiator with a one pipe low pressure steam system? The objective is to control room temperature with a thermostat. Is it better to use a thermostatic radiator valve + air vent? If you can do either, which will provide better temperature control of the room? Please note that we are NOT trying to throttle the steam (one cannot do that); the valve would be either open or closed and only act as a shutoff valve.