I have been told that a lot of people are having problems with PEX because to mice, the tubing tastes like cheese.
I do know that mice will chew the plastic coating on data cabling wire, so I am not surprised some might go after PEX.
It is in a lot of houses, and most folks never have anhy problem, It is just a personal preference for me.
Like I will not put an elect wire anywhere in the house smaller than 12 gauge , but most houses are fine with most circuits on 14 gauge.