I'm glad this thread has come back up, because I missed it the first time around. I have to agree with the theory that the grunt in "John Cherokee" was added by the Pacific Northwest folks, sometime in the late 1980s. When I moved from Mystic to San Francisco in 1990 I was taken aback by the resounding grunts that accompanied my first performance of that song at the Hyde St. chantey sing. We never did the grunt at Mystic in the 1980s, but it was clearly a well established tradition in SF in 1990. When I asked about it I was told that it was the Victory Sings people who introduced it at one of the SF Festivals of the Sea.