The simple fact is that aluminium bottles are inferior to stainless for a variety of safety and reliability reasons. First, raw aluminium has been linked through many studies to Alzheimer's Disease, requiring such bottles to use a protective inner coating or lining. Aluminium bottle manufacturers use an oven enamel to coat their bottles to prevent the aluminium from leaching. While these linings appear to be reliable, it's possible the lining will flake off over time...especially if the bottle is dented or exposed to extreme environments. And it's not dish-washer safe.