On a related note - has ANYONE ever replaced major A/C parts and had a reliable system? That is, lasting many years?

I talked to an engineer at a factory that made window and auto A/C units years ago and he said: "It is almost impossible to properly purge and recharge/oil an existing auto A/C system, take good care of it instead and NEVER allow someone to "recharge it" ". I admit that was in 1998/1999, but still....

I have had numerous new and lightly used cars in 40 years. NEVER had had to 'recharge' any of their A/C units. My GMC truck went 285,000 before the condensor was hit by a rock. My Ford Rangers (so far) have all gone to end of life with working A/C. My Ford Van had working A/C on it when I sold it at something around 225,000.

Of course, I follow the instructions of an engineer I worked under at Addison Products/Heat Controller in 1980, same instructions given by home A/C people, gave me:
... The system is designed to move heat, let it do that.
... DO NOT block off vents, and run fan at 75% speed or higher at all times. (This maintains balance between low side and high side.)
... Point air away from you or mix in some heat if it's too cold, DO NOT run the fan on a low setting.
... Put a plastic or fiberglass (non metal) bug screen a few inches ahead of the condensor to keep bugs from clogging the fins up.

Of course, none of the above applies to the new "next generation" A/C in some new cars today, as their pumps are variable and they have a lot of monitoring on them. Old systems were dumb.