most of the strength in tubing comes from its outer diameter, not how thick the walls are.
copper is very soft, aluminum alloy is not.
With two tubes of comparable diameter, the tube with the greater wall thickness would be stronger, right? The bar diameter is constant, so to increase strength he'd have to increase wall thickness.
@drummerboy, if you have that kind of a equipment, I would get some nice stainless steel tubing and go nuts.