In the case of my hand-fired the baro is absolutely essential. The draft potential from the chimney is very high, I initially had the stove connected with out a damper, I had lots of problems with extremely hot pipes and difficulty regulating the fire. After I became "educated" here on this forum, I installed the baro and bought a man-o-meter. My preference is a barometric damper.
On the stoker the baro opens very little, under a high fire it will open slightly, however on a windy day I can tell when the wind is gusting simply by watching the baro flap. I feel that it would open quite a bit more if there were not other appliances running into the same flue that allow air flow into the flue continuously. I have the manometer connected continuously to the stoker stove pipe and check the draft out of habit when adding coal to the hopper.
I think I saw ALGORE hovering over my house with a "greenhouse gases" meter in his hand.
Meanwhile I have neighbors with oil heat keeping their t-stats at 60 and grumbling. It's a lot warmer in here. Other then using oil for the domestic hot water heater we are 100% coal fired here except for the occasional fire in the wood-fired insert on really cold days.