I have just completed my first bit of plastic plumbing using PEX piping which seems to be the more commonly used piping. I did have to produce a couple of tight bends that did put a bit of strain on adjacent fittings but not enough to cause leakage. I was wondering which of the two pipes was the more flexible? I chose PEX after reading that polybutylene was referred in the past as "lay flat" pipe which suggested it was the more rigid of the two.

Richard