Back in 1972, my family built an owner-builder house in San Pedro, CA. We used PVC for the water system, which was allowed on an experimental basis by the city of Los Angeles back then. We're still there, and the PVC still works fine. The city, however, no longer allows it, so they must have had some problems.
I haven't often had to do any work around the plumbing, but when I do, like changing a water stop, I take great care not to put any mechanical stress on it. The bendy feeling is certainly not confidence-inspiring.
If I were doing it again today (in fact, I am on another building), I'd go with "K" type copper.