I worked for a plumber in California during the change from lead solder to 60/40. When it comes to sweating pipe, there was a huge difference, the 60/40 seemed impossible to work with at first. But I learned how to flow it, we all learned how to. The technique is different, the heat is different, and the post-heat inflow of solder is what kept it water-tight. Little nuances, but ultimately not a deal breaker for copper pipe.
Pex is something I saw widely used overseas and was happy to see used here in the US. I dislike the stupid PEX crimp tool and its stupid price tag, so I have used shark bites with PEX with zero problems in my world. Easy peasy. The O-ring is not rubber, it is nitrile/neoprene, so it will last. My local water pressure is 80 PSI, too.
Oetiker is my favorite system, I use it wherever I can. Unfortunately, pushing that stiff polyethylene tubing over a barbed fitting does not inspire any confidence with me. Whenever I put PE over a barb, whether it's the Pex feeding my toilet, or a 3" tie-in to the fire hydrant in the street, I use a propane torch to heat and soften the plastic before pushing it over the barb, crimping it, and letting it cool. This thermoforms the barbs into the inner wall of the pipe and does not leak. They never leak, which is why the inspector doesn't like seeing you heat a water line with a torch. Anything proven to reduce headaches later is obviously forbidden in code, because people lose track of the point of what they're doing and overheat the plastic and ruin the job, and we can't have that, so it's a banned practice. Well, there are custom homes all over Lake Tahoe that don't have water leaks because that step wasn't skipped.
