That is true but aluminium requires less energy to recycle when you're finished with it. I have bikes made of steel, aluminium and carbon fibre. I don't worry

That is true but aluminium requires less energy to recycle when you're finished with it. I have bikes made of steel, aluminium and carbon fibre. I don't worry about the longevity of any of them. Hydro-formed aluminium is cheap, relatively light and easy to live with IMHO. Horses for courses. I also think geometry of a frame is far more important than frame material for things like comfort but that's a different story. i.e. how much can the seat post flex.