Copper Herms or Stainless Steel?

Why stainless steel might offer an advantage. Some argue that using copper for the herms coil would be best given that copper is more efficient at transferring heat than stainless steel. In fluid heat transfers such as brewing applications, the difference is negligible. Testing can show that the temperature of wort exiting the herms coil is always equal to the temperature of water in the HLT so using copper would not have made a difference.Stainless steel is easier to clean, strong, and holds up better over time in contact with acidic liquids such as beer.