i live in an appartament too
first floor though and i don't think my manager knows what i store on the porch, if you would i would be out of here. (knocks on the wood for that one)
We i too use copper but only for the botton i use al for the top just because i can anodize it and make it look pretty plus swiftech does it... they must know what they are doing. It also weighs less then copper and in case the flow stops there is less chanse of it melting unlike and acrylic top from a maze say.
But that would be the other way to go copper bottoms and acrilic/lexan (you name it) tops. Morphin1 does that seems to work out quite well for him. If i were you i would choose this option because there is less copper to machine so easier on you yet you get 0% corrosion because there is no al in the system