Many plumbers are taking a wait and see approch to PEX after what has happened with polybutene tubing. It seems to have many good qualities to it, freeze resistence one of them. It would seem, that the PEX may "be" a good product to use.
Copper tubing, has been around for quite a while, with a good warranty on it. For more information on copper, try the link below.
: Bud & Steve-
: PEX tubing is not a way of "ripping you off". It is a technology that is not new but just new to the US. It is an easier system to install. Note how I say system, the PEX and fittings have been all engineered for well over 25 years.
: If you are looking for endurance, check out the manufacturer's warranty on the product. PEX generally carries a 25 year wanrranty and copper caries a 1 year warranty until you put an aggressive fluid in it (water or even air).
: Just because it's different, don't assume it is cheap.