Really the only advantage I can see to the volcano style kettles is that it will bring water to a boil quickly if your cooking over an open flame...
Is this "volcano" design really considered faster boiling or more efficient than using a pot over an open fire? It seems like this design would be superior and make better use of a given amount of wood, but sometimes the theoretical doesn't live up to expectations in real use, so I wonder what folks really say about them.