I used schedule 80 for years without a problem, but I agree, it is not the best. There are other possible suspects. They do make a hose that is meant for permanent installation. I suspect that PEX would work well, and certainly cheaper and easier than copper, and wouldn't explode into bits. My current shop has copper, (and commercial dryer), but I wouldn't worry about the size of the air line really. As they say in air tools, you don't worry how long the run is, unlike with an extension cord, it is all a reservoir. And if you think about it, 1/2" copper pipe will certainly keep up with any demand you might put on it. Think an abrasive blaster, one of the biggest users I can think of, and the size of the orifice is certainly MUCH smaller than 1/2".