Snapped the water line on my GE 4 door fridge, splice it or replace the whole line?

I was in the same spot about three years ago with my old Whirlpool. The plastic tube going into the back cracked when I shifted the fridge to fix the ice maker. I tried the splice first because I had a compression fitting in the junk drawer and it held fine for a few months, then started weeping at the nut. Not a flood, but enough to warp the edge of the laminate floor. That was the end of my trust in splicing old plastic.

Funny how two people can have opposite luck with the same fix. I spliced the poly line on my old Maytag with a barbed brass insert and two hose clamps back in maybe 2015, and it's still dry today. My dad taught me that trick and he's done the same on a few fridges over the years. The key is you need the stiff insert inside the tube so the clamp doesn't crush the plastic, and snug the clamps down on either side of the barb. A compression nut on old brittle poly is a different story, I'll agree with the earlier poster on that part, but a proper barbed splice isn't a band aid. The real problem usally isn't the splice, it's the setup behind the fridge. Mine snapped the first time because the line was pulled tight with zero slack. When I put it back I coiled a generous loop of extra line back there and zip tied it loosely to the cabinet so the fridge can slide out a couple feet without the line ever going taut. Haven't had a crack since, and that loop has saved me at least twice when I was in a hurry cleaning. On the braided stainless question, my take is don't bother for the run into the fridge unless your plastic is crumbling everywhere. That rigid stuff fights you in tight quarters and can acutally rattle against the compressor over the years. If the rest of the tube feels firm when you pinch it, splice it, add slack, and forget about it. If it snaps if you barely bend it, then yes, replace the whole run.

One thing I'd add since you're pulling the line anyway: leave yourself a good length of slack coiled behind the fridge when you run the new one. I replaced mine a few years back and cut it almost exactly to length, wich meant every time the fridge got moved even a couple inches the line was under tension, and that's basicly what killed the original one in the first place. Also peek at what's actually on the wall end. If the previous owner used one of those saddle valves that clamps onto the pipe and pierces it, that's the part I'd swap out while the water's shut off, since they're notorious for clogging and dripping.

Agree with leaving the slack coil, that detail matters more than people think. When I swapped to braided stainless on mine I coiled the extra and stuck a piece of foam pipe insulation over the section that sat near the back panel, since the coil woud otherwise knock against the cabinet every time the compressor kicked on. Drove me crazy til I figured that out. Also double check the fitting at the fridge end before you buy anything, mine needed a little adapter to go from the plastic tube size to the braided hose and I had to make a second trip to the hardware store.

When I did mine I skipped all the guesswork by unscrewing the old fitting from the fridge inlet and bringing it to the hardware store in my pocket. Matched the threads on the spot instead of guessing sizes in the aisle and coming home wrong twice. Braided stainless went on with nothing fancier than two adjustable wrenches, one to hold the body and one to snug the nut. If I can do it after a career of killing every houseplant I own, you'll be fine.