Plastic has been used for just about every air line on every truck made in America for the last 20 years. The big bugaboo about plastic air lines got started cause some fool used cheap plastic from some home center, and blew the line.
Like anything, the skill ain't in the material, it's in the mechanic. Fittings for plastic tubing usually run the cost above using copper and soldering it. R-22 runs at head pressures of 300# and has thermal shock to contend with that make an air system look like a kids baloon, yet R-22 systems run every day in copper with silflos joynts.
Seems like most air systems I see are plumbed with undersize pipe cause the guy who installed it never heard of fluid resistance in a line.
Bottom line, if you don't know what you're doing, leave the job alone.