Sorry to jump into an old thread. But I read a couple of people implying or outright stating that copper lasts forever. I just couldn't sit on my hands. I prefer copper also. Primarily because it is clean, does not leach chemicals, and has antimicrobial properties.
However...Copper DOES NOT LAST FOREVER. Period. Sure...I suppose with perfectly neutral pH water, in a perfect installation, with minimal temperature changes, and no copper exposure to concrete, wood, dirt, rocks, or other metals.....then MAYBE it will last "forever," whatever that means.
But in the real word, no one hacks up a house like an electrician or a plumber. Now you can jump all over me and explain how "YOU" wouldn't hack up a house...but the reality is that nearly every old house I have worked on or owned had been hacked up by plumbers before I got there. So a proper installation is a dream in most cases. Even in new construction. Ever been on a job site? Seen walls out of plumb by more than 1"? This is common. VERY common. There is no magical sub-contracting crew out there that does things "right." They all think they do it right. But why do we spend our lives going behind them and re-doing their work?
Copper through pine studs in a tight hole can oxidize the copper and cause pin-holes in 20 year old pipe. I have seen it. Not sure what does it. Sap maybe? Possibly some chemical on the wood? But I have seen it. Pinholes wherever the copper touched the wood tight.
Rocks can have metal content and react with copper and eat pinholes into it.
Concrete, an alkaline, outright reacts with copper and eats holes in it over time. You should sleeve utilities in plastic pipe when running through concrete.
Copper, where joined improperly to galvanized (which is to be found in at least one place, often more, in nearly every old house), will have an electrolytic reaction and the junction will fail many years later.
As for brass/o-ring quick connect fittings: They use a rubber seal. However, so do many of the water supply lines that connect fixtures all over the house. The fixtures either have crimp connection or screw-on connections with rubber washers. EVERY toilet supply seals with a rubber seal. Many designs of supply shut-off valves rely on rubber seals. Washing machines (not considered permanent) often use the same hoses for 20 or 30 years without failure (this is a very bad idea...). And old rubber fittings often fail if you interact with them.
So I primarily have two points:
1) ANY type of plumbing can and will fail over time. Even copper. Even though I prefer copper.
2) Most household plumbing is riddled with rubber fittings. Rubber fittings that are installed as permanent installs. Sinks and fixtures are considered permanent. And these fittings often fail when you attempt to tighten a shut-off, etc. But they generally don't fail if you don't touch them. For decades.
That said, I have two sharkbites in my attic on a stick of 3/4" copper. I don't like it and sometime in the next year or two I am going to go up there and sweat the joints. Both are Elbows. Rubber fittings are fine. But I don't particularly like them in the ceiling.
As for using sharkbites on copper, as a permanent install, in a crawlspace? I say "absolutely." I see no reason not too. And if it fails, it takes 5 minutes to replace it. No cutting or sweating required.