I have rarely wanted to break a hen of broodiness--one time was when some idiot went broody in January. I had not read about the dunking method, but that you put them in a wire cage with no bedding so their bottom cools. The first years I kept chickens, we didn't have electricity so an incubator was not an option. Now I have it, but as off-grid solar so conceivably would worry about the drain during a long cloudy period. But in any case, as long as I have one broody hen, I'd MUCH rather let her handle it, because aside from the effort of maintaining an incubator--which is probably no more than keeping a hen fed and watered inside Chickland, the enclosure within our coop where we put a broody hen so the others can't keep laying eggs in her nest, and she's less likely to abandon the nest halfway through. But then! When the chicks hatch, she knows just what to do, and she keeps them all warm and fed and taught how to be a chicken. Once, we let a hen and her chicks out of the coop when they were 11 days old, and she led them straight to the sand pile, which I use in the garden. I guess she realized they needed grit for their gizzards, which I wouldn't have thought of.
Mostly I don't see why you'd want to break a hen of broodiness unless she's doing it off-season, or all your hens are going broody and you aren't getting eggs, or maybe you have no rooster so those eggs won't hatch. Right now I have two hens setting--which makes more of a dent in the egg supply than can be accounted for by the eggs under the hens and the hens out of the laying roster, it always seems--and someone coming to get a dozen fertilized ggs so she can replenish her flock after predators wiped out all but two hens.