So... If I had access to pipes (such as doing a remodel) I would just replace them. It's easy, and completely resets the clock. If you have some corrosive issue then use PEX instead of copper.

The thing is that there is a lot of discussion about chemical leaching, long-term effects of chlorine, physical wear (from water moving over it) with regard to both copper and PEX. Those issues have been determined at this point for copper and PEX... I don't know about epoxy.

I would also think that some of the long-term effects are really dependent on the installers: Was it mixed properly, was it cleaned properly, etc. I'm not sure how it could get NSF certification with the variables on each installation.

Also, how are repairs/modifications handled?

If it wasn't accessible (slab), I might be more willing to consider it... but would really try to go with what has a long history of use instead.

Thanks so much for the input... What is your preferred pipe? Copper or PEX?

Either are good. If I am doing home runs, I use PEX because it's cheaper and faster. If I have copper existing and just doing some minor changes, I stay with copper.