That thunk is like a rite of passage for old houses, isn’t it? I remember the first time I heard it after moving in, I thought something was about to burst. Turns out, just copper doing its thing. I get what you mean about PEX feeling a little sketchy behind drywall, though. When I swapped out my tub for a shower last year, I went back and forth on this exact debate.
I ended up using PEX for most of the run, mainly because the crawlspace under my bathroom is a nightmare and there’s no way I was getting copper in there without losing my mind. The flexibility was a lifesaver, but I definitely spent way too long double-checking every crimp and connection. There’s something about not being able to see or hear what’s going on behind the wall that makes me a little paranoid. I actually wrapped the PEX in those cheap foam sleeves just in case any critters decided to get curious. Not sure if it’ll help, but it made me feel better.
I haven’t had a joint pop yet (knock on wood), but I did have one that wasn’t crimped tight enough and started weeping after a week. Luckily, it was in an accessible spot, but it made me rethink how much I trust those connections where I can’t see them. Still, the speed and lack of torch burns are hard to argue with. My hands are grateful.
Copper definitely feels more “real” somehow—like you know it’s going to last forever if you do it right. But for weird angles and tight spaces, PEX is just so much easier. I guess it comes down to whether you want peace of mind or convenience. Either way, sounds like you’ve got the right idea being cautious about what goes behind the walls.