I have experienced Pex freezing last winter with no issues.
I had removed all existing water lines and plumbed all water lines with Pex, before heading south.
I winter in southern TX, while there my furnace decided to quit working. When my son-in-law checked on my house and found no water flowing from the spigots. He shut off the city water supply inside the home, shut off all gas lines, opened the most upper and most lower spigots, opened the drain on water heater and left.
Upon arriving home in April the only problem was a frozen and split ball **** shutoff before the water meter, also frozen water meter.
Luckily the ball **** was split above the ball so no water would flow. Had city shut off outside, changed ball **** shutoff and water meter. Everything else held secure thanks to the Pex. That experience made me a believer in Pex