FWIW I have a full set of Pex tools and fittings. I own two houses that were plumbed with PBT (polybutylene tubing) which is the gray stuff that fails when exposed to water treated with chlorine. Our houses were on well water up until around 15 years ago, when we switched to city water, now the fittings are failing.
So when one fails I replace from the fixture down to the main run with Pex, eventually I will replace the main runs too.
Sharkbite fittings are great for repairs and I keep a few in my RV spares box. Too expensive to use for a full house plumbing job.